Splits groebner.jl into parts

[ederc]

This PR splits groebner.jl into meaningful parts. It adds a global groebner/groebner.jl file that just includes all other parts like it is done in Groups.

[joschmitt]

Thank you!

[joschmitt]

This has some potential for merge conflicts, but right now the only pull request that edits this file is #4244 from what I can see.

[codecov]

Codecov Report

Attention: Patch coverage is 89.80044% with 46 lines in your changes missing coverage. Please review.

Project coverage is 84.59%. Comparing base (16517cf) to head (841ddb5).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Rings/groebner/hilbert-driven.jl	67.81%	28 Missing ⚠️
src/Rings/groebner/modular.jl	92.95%	5 Missing ⚠️
src/Rings/groebner/f4.jl	73.33%	4 Missing ⚠️
src/Rings/groebner/general.jl	93.33%	4 Missing ⚠️
src/Rings/groebner/leading-ideal.jl	77.77%	2 Missing ⚠️
src/Rings/groebner/fglm.jl	95.83%	1 Missing ⚠️
src/Rings/groebner/generators.jl	96.29%	1 Missing ⚠️
src/Rings/groebner/highest-corner.jl	90.90%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4250   +/-   ##
=======================================
  Coverage   84.59%   84.59%           
=======================================
  Files         631      640    +9     
  Lines       85072    85072           
=======================================
  Hits        71970    71970           
  Misses      13102    13102           

Files with missing lines	Coverage Δ
src/Rings/groebner/reduce.jl	100.00% <100.00%> (ø)
src/Rings/groebner/transformation-matrix.jl	100.00% <100.00%> (ø)
src/Rings/groebner/fglm.jl	95.83% <95.83%> (ø)
src/Rings/groebner/generators.jl	96.29% <96.29%> (ø)
src/Rings/groebner/highest-corner.jl	90.90% <90.90%> (ø)
src/Rings/groebner/leading-ideal.jl	77.77% <77.77%> (ø)
src/Rings/groebner/f4.jl	73.33% <73.33%> (ø)
src/Rings/groebner/general.jl	93.33% <93.33%> (ø)
src/Rings/groebner/modular.jl	92.95% <92.95%> (ø)
src/Rings/groebner/hilbert-driven.jl	67.81% <67.81%> (ø)