Avoid copying examples when building tests

[jwallwork23]

Closes #279.

Simplifies the developer experience, as discussed in today's meeting.

• FTorch/src/CMakeLists.txt moved to FTorch/CMakeLists.txt.
• FTorch/src/tests/ moved to FTorch/tests/.
• No longer any need to copy the examples when building FTorch with test support.
• Updated docs accordingly.
• Added API change note.

[jatkinson1000]

Hi @jwallwork23 CMake adjustments look fine, but I think you need to update the installation instructions on the main README and in the pages/ directory to reflect that users no longer build in src/build/.

Would be worth a comb through the rest of the READMEs and docs to check for anything else that may need changing.

[jwallwork23]

Hi @jwallwork23 CMake adjustments look fine, but I think you need to update the installation instructions on the main README and in the pages/ directory to reflect that users no longer build in src/build/.

Would be worth a comb through the rest of the READMEs and docs to check for anything else that may need changing.

Thanks @jatkinson1000 - I think I covered everything with e0e85d3. Grepped for src and updated anything needed.

[jatkinson1000]

Thanks @jwallwork23 On the assumption you catched 'em all I'm happy to approve this.