Move existing comparision code to types

[AlekSi]

With minimal code changes.

Refs #481.

[codecov]

Codecov Report

Merging #531 (8e9798b) into main (f6bfa76) will decrease coverage by 0.06%.
The diff coverage is 77.61%.

@@            Coverage Diff             @@
##             main     #531      +/-   ##
==========================================
- Coverage   63.79%   63.73%   -0.07%     
==========================================
  Files         116      119       +3     
  Lines        6522     6521       -1     
==========================================
- Hits         4161     4156       -5     
- Misses       1823     1828       +5     
+ Partials      538      537       -1     

Impacted Files	Coverage Δ
internal/handlers/common/sorttype_string.go	0.00% <0.00%> (ø)
internal/types/compareresult_string.go	0.00% <0.00%> (ø)
internal/handlers/common/match.go	48.27% <48.27%> (ø)
internal/handlers/common/projection.go	55.55% <57.14%> (ø)
internal/handlers/common/sort.go	53.48% <75.00%> (ø)
internal/types/compare.go	92.35% <92.35%> (ø)
internal/handlers/common/error.go	80.70% <100.00%> (+5.14%)	⬆️
internal/handlers/common/filter.go	85.13% <100.00%> (-0.06%)	⬇️

Flag	Coverage Δ
FerretDB	52.07% <70.14%> (-0.07%)	⬇️
MongoDB	6.62% <0.00%> (+<0.01%)	⬆️
integration	52.10% <70.14%> (-0.07%)	⬇️
unit	40.40% <23.88%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.