Add TODOs

[AlekSi]

Readiness checklist

• I added tests for new functionality or bugfixes.
• I ran task all, and it passed.
• I added/updated comments for both exported and unexported top-level declarations (functions, types, etc).
• I checked comments rendering with task godocs.
• I ensured that the title is good enough for the changelog.
• (for maintainers only) I set Reviewers (@FerretDB/core), Assignee, Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

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Name	Status	Preview	Updated
ferret-db	✅ Ready (Inspect)	Visit Preview	Nov 30, 2022 at 0:50AM (UTC)

[codecov]

Codecov Report

Merging #1595 (66bd49b) into main (3cdd0be) will decrease coverage by 0.20%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1595      +/-   ##
==========================================
- Coverage   67.74%   67.53%   -0.21%     
==========================================
  Files         284      284              
  Lines       13813    13825      +12     
==========================================
- Hits         9357     9337      -20     
- Misses       3499     3530      +31     
- Partials      957      958       +1     

Impacted Files	Coverage Δ
ferretdb/ferretdb.go	80.28% <100.00%> (ø)
integration/setup/common.go	94.24% <100.00%> (+0.39%)	⬆️
integration/setup/common_unix.go	86.48% <100.00%> (+1.19%)	⬆️
internal/handlers/tigris/tigrisdb/errors.go	21.42% <0.00%> (-21.43%)	⬇️
internal/handlers/tigris/tigrisdb/databases.go	57.50% <0.00%> (-10.00%)	⬇️
internal/handlers/tigris/msg_create.go	67.60% <0.00%> (-7.05%)	⬇️
internal/handlers/tigris/tigrisdb/collections.go	61.90% <0.00%> (-4.77%)	⬇️
internal/util/version/version.go	48.52% <0.00%> (-4.42%)	⬇️
internal/handlers/pg/pgdb/collections.go	52.27% <0.00%> (-2.28%)	⬇️
internal/handlers/pg/pgdb/settings.go	44.21% <0.00%> (-2.05%)	⬇️
... and 1 more

Flag	Coverage Δ
integration	63.46% <92.85%> (-0.21%)	⬇️
mongodb	13.90% <28.57%> (-0.01%)	⬇️
pg	52.34% <92.85%> (-0.07%)	⬇️
tigris	36.80% <50.00%> (-0.13%)	⬇️
unit	26.79% <100.00%> (-0.03%)	⬇️

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[rumyantseva]

LGTM