Export integration tests helpers

[AlekSi]

They are needed for Tigris integration.

[codecov]

Codecov Report

Merging #838 (d61f9e8) into main (4ddc06b) will increase coverage by 29.37%.
The diff coverage is 75.00%.

@@             Coverage Diff             @@
##             main     #838       +/-   ##
===========================================
+ Coverage   29.70%   59.08%   +29.37%     
===========================================
  Files         217      217               
  Lines        9817     9817               
===========================================
+ Hits         2916     5800     +2884     
+ Misses       6438     3306     -3132     
- Partials      463      711      +248     

Impacted Files	Coverage Δ
integration/setup.go	84.09% <75.00%> (+28.03%)	⬆️
internal/util/version/version.go	55.00% <0.00%> (-5.00%)	⬇️
internal/bson/document.go	47.09% <0.00%> (+0.68%)	⬆️
internal/types/document.go	85.02% <0.00%> (+1.79%)	⬆️
internal/types/types.go	85.88% <0.00%> (+2.35%)	⬆️
integration/helpers.go	85.41% <0.00%> (+2.77%)	⬆️
internal/types/path.go	84.21% <0.00%> (+4.21%)	⬆️
internal/handlers/pg/pgdb/settings.go	37.20% <0.00%> (+6.97%)	⬆️
internal/clientconn/conn.go	46.38% <0.00%> (+10.26%)	⬆️
internal/types/compare_order.go	82.50% <0.00%> (+11.25%)	⬆️
... and 55 more

Flag	Coverage Δ
FerretDB	61.29% <75.00%> (?)
MongoDB	7.23% <75.00%> (-0.04%)	⬇️
integration	61.39% <75.00%> (+54.11%)	⬆️
unit	27.64% <ø> (ø)

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

[rumyantseva]

LGTM