Enable osign gtest suite under CTest

[Hathor875]

Part of #93
Port the osign library from qmake to CMake and register its GoogleTest suite with CTest. This was the last un-migrated gtest suite in the list tracked by issue #93, blocked only by the missing osign build target.

The suite needs no fixtures — it generates its own passwords and certificates at run time — so the target needs neither staged data nor a custom WORKING_DIRECTORY.

Notes on the translation of osign.pro:

• common_openssl.cpp is compiled into the library. osign.pro pulls it in through "CONFIG += open_ssl_common" (openssl.pri) and certificate.cpp calls NSOpenSSL::PBKDF2 and AES_*_desktop_GCM, so the test executable does not link without it.
• Base64.cpp and File.cpp are deliberately not compiled in. The .pro compiled them directly because qmake did not link kernel; the CMake target links kernel, which already provides NSBase64 and NSFile.
• KERNEL_USE_DYNAMIC_LIBRARY_BUILDING is not carried over. In the .pro it only served to export those two files from osign; the target now wants KERNEL_DECL = Q_DECL_IMPORT.
• src/Certificate_openssl.h and the support_oform block are dropped — neither header exists under osign/lib/src and no source includes them.
• The core_windows link list is ported verbatim but is untested here, as the port was developed and verified on Linux.

Unlike ooxmlsignature — which x2tlib pulls into the default build — osign has no non-test consumer, so it is reached only through the test's guarded add_subdirectory, and nothing changes when EO_BUILD_TESTS is OFF.

Verified locally: osign_test builds from a clean target directory and reports 6/6 passing; the seven other built CTest suites still pass alongside it.
Built on Fedora, which needs two local deviations from TESTING.md (not part of this PR): libstdc++-static installed, and third-party deps built beforehand so -DTHIRD_PARTY_PREPARED=TRUE can skip the V8 step, which needs clang-13. osign does not depend on V8.

Assisted-by: Claude Code:claude-opus-5

Tests

$ cd ~/euro/core && export VCPKG_ROOT=/var/home/krzysztofc/vcpkg && \
  cmake -GNinja -S . -B build \
    -DTHIRD_PARTY_PREPARED=TRUE \
    -DVCPKG_TARGET_TRIPLET=x64-linux-dynamic \
    -DCMAKE_TOOLCHAIN_FILE="$VCPKG_ROOT/scripts/buildsystems/vcpkg.cmake" \
    -DVCPKG_MANIFEST_MODE=ON -DVCPKG_MANIFEST_DIR=. \
    -DVCPKG_MANIFEST_FEATURES=tests -DEO_BUILD_TESTS=ON && \
  rm -rf build/osign_test build/package/libosign.so.1 && \
  cmake --build build --target osign_test && \
  ctest --test-dir ~/euro/core/build -R osign_test -V

[... vcpkg install + cmake configure trimmed ...]
-- Configuring done (24.8s)
-- Generating done (0.2s)
-- Build files have been written to: /var/home/krzysztofc/euro/core/build

[5/12] Building CXX object osign_test/osign/CMakeFiles/osign.dir/src/certificate.cpp.o
certificate.cpp:153:39: warning: suggest parentheses around comparison in operand of '=='
  153 |  if (1 != ASN1_STRING_set(serialNumber, pSerialNumber, nBytesCount) == 1)
[... two -Wunused-value warnings from OpenSSL's BIO_flush macro trimmed ...]
[7/12] Creating library symlink osign_test/osign/libosign.so
🎉  Success! [libosign.so.1] is ready!  🎉
[9/12] Linking CXX executable osign_test/osign_test

9: Test command: /var/home/krzysztofc/euro/core/build/osign_test/osign_test
9: Working Directory: /var/home/krzysztofc/euro/core/build/osign_test
9:  LD_LIBRARY_PATH=/var/home/krzysztofc/euro/core/build/package:/var/home/krzysztofc/euro/core/build/vcpkg_installed/x64-linux-dynamic/lib:
9: [==========] Running 6 tests from 1 test suite.
9: [       OK ] COSignTest.crypt_storage_aes_gcm_random_password (1 ms)
9: [       OK ] COSignTest.crypt_storage_aes_gcm_string_password (0 ms)
9: [       OK ] COSignTest.serialize_buffer_string (0 ms)
9: [       OK ] COSignTest.sign_buffer_string (0 ms)
9: [       OK ] COSignTest.serialize_storage_by_sign (0 ms)
9: [       OK ] COSignTest.serialize_storage_by_property (0 ms)
9: [  PASSED  ] 6 tests.
1/1 Test #9: osign_test .......................   Passed    0.02 sec

100% tests passed, 0 tests failed out of 1

The -Wparentheses warning above is pre-existing and cosmetic: certificate.cpp:153
reads if (1 != ASN1_STRING_set(...) == 1), which parses as (1 != ...) == 1 and is
therefore true exactly when the call fails, so the fallback behaves as intended.
Not touched here.

No regressions in the suites already migrated:

$ ctest --test-dir ~/euro/core/build -E test_odf
Test project /var/home/krzysztofc/euro/core/build
1/8 Test #1: cfcpp_test .......................   Passed    0.15 sec
2/8 Test #2: booleanoperations_test ...........   Passed    0.01 sec
3/8 Test #3: starmath_smconverter_test ........   Passed    0.01 sec
4/8 Test #4: starmath_eqntoooxml_test .........   Passed    0.00 sec
5/8 Test #5: ooxml_test .......................***Not Run   0.00 sec
6/8 Test #6: officeutils_test .................   Passed    0.01 sec
7/8 Test #7: starmath_smcustomshape_test ......   Passed    0.00 sec
8/8 Test #8: osign_test .......................   Passed    0.01 sec

100% tests passed, 0 tests failed out of 7

ooxml_test and test_odf were not built in this tree, hence the "Not Run" and the
exclusion — ooxml_test is additionally marked DISABLED in the repo. Everything that
was built passes.

[chrip]

The engineering is correct and I could not fault a single translation decision;
the only substantive finding is a one-line factual error that would otherwise be baked into
repo documentation. Two things before merge:

1. Reword the ooxmlsignature comparison in TESTING.md. The new block currently ends:

Like ooxmlsignature, the library is not part of the default build: it is reached only
through the test's guarded add_subdirectory.

ooxmlsignature is in the default build — CMakeLists.txt:22 →
X2tConverter/build/cmake/CMakeLists.txt:11 →
X2tConverter/build/cmake/library/CMakeLists.txt:124-126, where x2tlib adds
DesktopEditor/xmlsec/src with no EO_BUILD_TESTS gate. Keeping osign test-only is still the
right call — nothing in x2tlib or the DocumentServer packaging references it — so only the
comparison is wrong. Suggested replacement:

Unlike ooxmlsignature — which x2tlib pulls into the default build — osign has no
non-test consumer, so it is reached only through the test's guarded add_subdirectory
and nothing changes when EO_BUILD_TESTS is OFF.

The same sentence appears in the PR description and the commit message; worth fixing there too,
but TESTING.md is the copy that becomes permanent repo documentation.

2. CI approval — on me, not you. Nothing beyond the DCO check has run: the Build, Build
(Windows x64) and Build WASM runs are all sitting in action_required. As a first-time
contributor with read access pushing from a fork, you cannot release them yourself, so there is
nothing for you to do here — I'll approve the runs so the Linux job actually compiles osign
and executes osign_test.

With the reword in and a green Linux build, this is a straightforward approve. Nice, careful
piece of work otherwise — every translation decision in the description held up when I checked
it against the sources.

Assisted-by: ClaudeCode:claude-opus-5

[Hathor875]

Thanks for catching that. Will verify the x2tlib chain and fix the wording in TESTING.md, the commit message and the PR description.

Understood on CI.

[Hathor875]

@chrip
Fixed in d6a1ae0 .

Two notes on CI:

• Windows fails during configure while fetching V8 via depot_tools, before anything compiles — same failure as on several unrelated branches. osign does not depend on V8.
• Linux was cancelled at the 6h job limit, not failed, so it never got to build osign or run osign_test.