Use git_remote_url throughout instead of a mix with hand-constructed links.

[hmgaudecker]

• Was using different links in setup.cfg
• Now git_remote_url everywhere, must have the form https://github.com/<user or organisation name>/<repo name>
• Add assert statements and tests
• Explain in dialogue

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.81%. Comparing base (eda143b) to head (1af30db).
Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
hooks/post_gen_project.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #144      +/-   ##
==========================================
+ Coverage   58.49%   60.81%   +2.32%     
==========================================
  Files           3        3              
  Lines         159      171      +12     
==========================================
+ Hits           93      104      +11     
- Misses         66       67       +1     

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[hmgaudecker]

Irrelevant with #149