Introduce -inf as potential output for the dimension of an ideal

[HechtiDerLachs]

Address #2721 .

[HechtiDerLachs]

Tests seem to pass. Good to go from my side.

[thofma]

Hm, is this correct if the coefficient ring is not a field?

[HechtiDerLachs]

I guess you're right. It was probably wrong before, but we should correct it.

[codecov]

Codecov Report

Attention: Patch coverage is 92.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 84.40%. Comparing base (d6230ef) to head (67ae9ac).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
experimental/Schemes/src/Resolution_structure.jl	83.33%	1 Missing ⚠️
...ebraicGeometry/Schemes/Divisors/AlgebraicCycles.jl	0.00%	1 Missing ⚠️
src/Rings/mpoly-ideals.jl	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4393      +/-   ##
==========================================
+ Coverage   84.38%   84.40%   +0.01%     
==========================================
  Files         656      656              
  Lines       87198    87216      +18     
==========================================
+ Hits        73583    73613      +30     
+ Misses      13615    13603      -12     

Files with missing lines	Coverage Δ
...y/Schemes/AffineAlgebraicSet/Objects/Properties.jl	100.00% <100.00%> (ø)
...ometry/Schemes/AffineSchemes/Objects/Attributes.jl	91.72% <100.00%> (ø)
...metry/Schemes/CoveredSchemes/Objects/Attributes.jl	85.93% <100.00%> (ø)
...ry/Schemes/ProjectiveSchemes/Objects/Attributes.jl	87.75% <100.00%> (ø)
.../AlgebraicGeometry/Schemes/Sheaves/IdealSheaves.jl	81.53% <100.00%> (ø)
src/Rings/MPolyQuo.jl	92.08% <100.00%> (ø)
src/Rings/mpoly-affine-algebras.jl	82.58% <100.00%> (ø)
src/Rings/mpoly-localizations.jl	77.82% <100.00%> (+0.16%)	⬆️
src/Rings/mpoly.jl	72.23% <100.00%> (ø)
src/Rings/mpolyquo-localizations.jl	74.46% <100.00%> (+0.01%)	⬆️
... and 3 more

... and 1 file with indirect coverage changes