feat: add C2xC2 extension with given discriminant

[thofma]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 72.97297% with 10 lines in your changes missing coverage. Please review.

Project coverage is 75.96%. Comparing base (7344274) to head (1ccb8e9).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/FieldFactory/ab_exts.jl	72.97%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1712      +/-   ##
==========================================
- Coverage   75.97%   75.96%   -0.01%     
==========================================
  Files         361      361              
  Lines      114341   114377      +36     
==========================================
+ Hits        86868    86888      +20     
- Misses      27473    27489      +16     

Files with missing lines	Coverage Δ
src/FieldFactory/ab_exts.jl	84.37% <72.97%> (+4.15%)	⬆️

... and 33 files with indirect coverage changes