feat: add dynamic file structures in loop using yield-tag

[kj-9]

What I did:

• Added a new Jinja extension in copier/jinja_ext.py to handle yield tags
  • This is a lightweight extension that detects yield tags and sets up the necessary context through jinja_env
• Updated _render_path to return multiple destination paths and their corresponding contexts when yield tags are present
  • Internally, delegated the recursive logic for generating paths and contexts from yield tags to the _render_parts function
• Added extra_context parameter to _render_file to enable injection of contexts generated from yield tags

[kj-9]

hopefully closes #1271

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.91%. Comparing base (8391966) to head (bc99b0d).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1855      +/-   ##
==========================================
+ Coverage   97.67%   97.91%   +0.23%     
==========================================
  Files          49       51       +2     
  Lines        5238     5359     +121     
==========================================
+ Hits         5116     5247     +131     
+ Misses        122      112      -10     

Flag	Coverage Δ
unittests	97.91% <100.00%> (+0.23%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

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

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[yajo]

I only reviewed tests in depth so far, and it seems the interface is almost exactly what I meant! Awesome!

Quoting from #1271 (comment):

are you rendering a filename?
No: just let the exception raise and print a nice message "Using yield outside of file names isn't supported".

That seems to be the only missing part. At least I saw no test for that. Could you add this please?

When done I'll review the implementation. This PR is big!

Thank you very much 😊

[kj-9]

@yajo

Thank you for your review!

I've added a new commit that implements the behavior you mentioned - throwing an exception when yield is used for rendering file contents. I've also added the corresponding test case.

Looking forward to your implementation review!

[pawamoy]

pass is unnecessary if there's a docstring 🙂

Suggested change

	pass