Refactor celix_container_bundles_dir to use add_custom_target

[pnoltes]

This PR addresses an issue where changes to bundle zip files were not being copied to the "bundles" directory in the container.

The process of copying updated bundles to a container "bundles" dir appears to have broken at some point. Unfortunately, I couldn't trace back the specific change that introduced this issue using git blame.

Originally, the copying of bundles was tracked with a timestamp file, in combination with a CMake add_custom_command. However, attempts to resolve the problem with the add_custom_command proved unsuccessful, leading me to replace it with add_custom_target.

In my opinion, a custom target is less than ideal, as a custom target dependency always triggers whenever a target is built. A comparison of the time to run make -j when nothing has changed demonstrated that on my systems, it took twice as long (albeit still under 1 second).

An upside is that the current change seems to fix the usage CMake -> Ninja, which I previously had issues with. Building with ninja, compared to make -j, is significantly faster.

In conclusion, despite its drawbacks, I believe this update is necessary for now to resolve the issue. Possibly in the future, we can revert to using add_custom_command instead of add_custom_target.

[codecov-commenter]

Codecov Report

Merging #594 (aece685) into master (456de19) will decrease coverage by 0.52%. The diff coverage is n/a.

:exclamation: Current head aece685 differs from pull request most recent head 3b55bfb. Consider uploading reports for the commit 3b55bfb to get more accurate results

@@            Coverage Diff             @@
##           master     #594      +/-   ##
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- Coverage   79.00%   78.48%   -0.52%     
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  Files         234      234              
  Lines       35386    35386              
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- Hits        27955    27772     -183     
- Misses       7431     7614     +183     

see 8 files with indirect coverage changes

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[PengZheng]

Originally, the copying of bundles was tracked with a timestamp file, in combination with a CMake add_custom_command. However, attempts to resolve the problem with the add_custom_command proved unsuccessful, leading me to replace it with add_custom_target.

We have already done this timestamp thing several times successfully in BundlePackaging.cmake. I am curious why it didn't work this time.

[pnoltes]

We have already done this timestamp thing several times successfully in BundlePackaging.cmake. I am curious why it didn't work this time.

I agree, I would like to test if this broke with a newer cmake. But for now a fix with custom targets is IMO good enough.