Rename, extend, document and test all_monomials

[joschmitt]

• I renamed all_monomials, which gives an iterator over all monomials of a polynomial ring of a given degree, to the more appropriate monomials_of_degree and exported (+test, document) this function.
• I added the variant monomials_of_degree(::MPolyRing, ::Int, ::UnitRange) which only works on a subset of the variables specified by the range and which should cover the use case in Draft - InvRing for SLn #2823 .
• I decided to make it throw an error for non-standard graded rings. So far it works for those rings by ignoring the grading. @HechtiDerLachs is this fine for you? I don't want to break your code or use case.

[codecov]

Codecov Report

Merging #3025 (7e83ac1) into master (ad349a2) will increase coverage by 0.00%.
The diff coverage is 87.03%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3025   +/-   ##
=======================================
  Coverage   80.09%   80.10%           
=======================================
  Files         491      491           
  Lines       69349    69381   +32     
=======================================
+ Hits        55547    55576   +29     
- Misses      13802    13805    +3     

Files	Coverage Δ
src/InvariantTheory/helpers.jl	88.57% <ø> (ø)
src/InvariantTheory/secondary_invariants.jl	99.52% <100.00%> (ø)
src/Modules/UngradedModules.jl	83.25% <100.00%> (ø)
src/Rings/mpolyquo-localizations.jl	74.38% <100.00%> (ø)
src/InvariantTheory/types.jl	99.10% <90.90%> (-0.90%)	⬇️
src/Modules/Iterators.jl	75.00% <66.66%> (ø)
src/InvariantTheory/iterators.jl	91.79% <85.29%> (-0.33%)	⬇️

... and 1 file with indirect coverage changes

[thofma]

Looking at the coverage, there seem to be a few (changed) lines missing. Did you test this locally or do we hope that nothing breaks?

[HechtiDerLachs]

Fine with me. Thanks for the notification!

[joschmitt]

Looking at the coverage, there seem to be a few (changed) lines missing. Did you test this locally or do we hope that nothing breaks?

I added more tests now so that the actual iterator should be covered completely. Otherwise it is the renaming of a so far not exported function, so I hope it is fine?

[thofma]

I added more tests now so that the actual iterator should be covered completely. Otherwise it is the renaming of a so far not exported function, so I hope it is fine?

Sure. I will merge once CI shows green.