options: Add support for path using std::filesystem::path

[mwestphal]

• Add a _option_variant_convert logic in f3dOptions.cmake for conversion from an option type to a variant type
• Add path aka std::filesystem::path has a valid option type
• Add parse/format for path
• Use path for hdri.file, font_file, all texture options
• Add functionnal, unit and coverage testing
• Add doc
• Added deprecation code for collapse behavior

related to #1570

[github-actions]

You are modifying libf3d public API! ⚠️Please update bindings accordingly⚠️!
You can find them in their respective directories: python, java, webassembly.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.80%. Comparing base (9d5bc10) to head (ab23b1f).
Report is 25 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2046      +/-   ##
==========================================
+ Coverage   95.79%   95.80%   +0.01%     
==========================================
  Files         128      128              
  Lines       10485    10499      +14     
==========================================
+ Hits        10044    10059      +15     
+ Misses        441      440       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Meakk]

Small typo, but otherwise it looks good.
I still would like to clarify if we still need the variant, or if we can get rid of variant and actual types, but it's out of scope of this PR

[mwestphal]

I still would like to clarify if we still need the variant, or if we can get rid of variant and actual types, but it's out of scope of this PR

We still need it, but we could deprecate it and remove the API on the next release. Ill open an issue.

[mwestphal]

#2054