CCL modes

[vitenti]

Description

Introduce CCL modes to allow running Firecrown with CCL in non calculator mode.

Also:

• Fixes Too many examples in the same directory #335
• Replace Mu sigma firecrown #458

Type of change

Please delete the bullet items below that do not apply to this pull request.

• New feature (non-breaking change which adds functionality)
• Refactoring
• This change requires a documentation update

Checklist:

• I have run bash pre-commit-check and fixed any issues
• I have added tests that prove my fix is effective or that my feature works
• I have made corresponding changes to the documentation
• I have 100% test coverage for my changes (please check this after the CI system has verified the coverage)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.9%. Comparing base (96b38ba) to head (33213a4).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #465     +/-   ##
========================================
+ Coverage    98.7%   98.9%   +0.1%     
========================================
  Files          54      54             
  Lines        4066    4155     +89     
========================================
+ Hits         4015    4110     +95     
+ Misses         51      45      -6     

Files with missing lines	Coverage Δ
firecrown/ccl_factory.py	100.0% <100.0%> (ø)
firecrown/connector/cobaya/likelihood.py	100.0% <100.0%> (ø)
firecrown/connector/cosmosis/likelihood.py	97.4% <100.0%> (+<0.1%)	⬆️
firecrown/connector/numcosmo/numcosmo.py	99.7% <100.0%> (+<0.1%)	⬆️
firecrown/likelihood/factories.py	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes