DOC: Expose options for keeping the old layout with doxygen v1.13.2

By upgrading doxygen version from 1.9.6 to 1.13.2, the defaults for these settings changed from:

GENERATE_TREEVIEW = NO
DISABLE_INDEX = NO

to

GENERATE_TREEVIEW = YES
DISABLE_INDEX = YES

Co-authored-by: Albert GitHub <albert.tests@gmail.com>

Author: dzenanz

Utilities/Doxygen/DoxygenConfig.cmake

@@ -57,6 +57,8 @@ set(DOXYGEN_FILTER_SOURCE_FILES "YES")
 set(DOXYGEN_SOURCE_BROWSER "YES")
 set(DOXYGEN_REFERENCED_BY_RELATION "YES")
 set(DOXYGEN_REFERENCES_RELATION "YES")
+set(DOXYGEN_GENERATE_TREEVIEW "YES")
+set(DOXYGEN_DISABLE_INDEX "YES")
 set(DOXYGEN_HTML_HEADER "${ITK_SOURCE_DIR}/Documentation/Doxygen/DoxygenHeader.html")
 set(DOXYGEN_HTML_FOOTER "${ITK_SOURCE_DIR}/Documentation/Doxygen/DoxygenFooter.html")
 set(DOXYGEN_HTML_EXTRA_FILES "${ITK_SOURCE_DIR}/Utilities/Doxygen/serviceWorker.js"