Add simplest validation to check data documents

[rumyantseva]

Description

This PR closes #693.

In this solution we introduce (d *Document) ValidateData() error method to validate documents representing data.
We use this method to solve what's needed in #693.

Tests are present in FerretDB/dance#211.

Tigris will be covered in the same Sprint in a separate task #1248 (to make tigrisdb similar to pgdb).

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.

[vercel]

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Name	Status	Preview	Updated
ferret-db	✅ Ready (Inspect)	Visit Preview	Oct 17, 2022 at 5:29AM (UTC)

[codecov]

Codecov Report

Merging #1246 (e67286e) into main (c363ece) will decrease coverage by 0.27%.
The diff coverage is 52.77%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1246      +/-   ##
==========================================
- Coverage   66.64%   66.37%   -0.28%     
==========================================
  Files         269      270       +1     
  Lines       12574    12609      +35     
==========================================
- Hits         8380     8369      -11     
- Misses       3296     3331      +35     
- Partials      898      909      +11     

Impacted Files	Coverage Δ
internal/handlers/pg/msg_insert.go	40.00% <0.00%> (-2.26%)	⬇️
internal/handlers/pg/pgdb/insert.go	30.76% <0.00%> (-4.02%)	⬇️
internal/handlers/pg/pgdb/update.go	60.86% <0.00%> (-9.14%)	⬇️
internal/handlers/pg/msg_update.go	57.60% <50.00%> (-0.68%)	⬇️
internal/types/document_validation.go	87.50% <87.50%> (ø)
internal/util/version/version.go	48.52% <0.00%> (-4.42%)	⬇️
internal/handlers/pg/pgdb/query.go	51.41% <0.00%> (-2.83%)	⬇️
internal/handlers/common/filter.go	86.58% <0.00%> (-2.21%)	⬇️

Flag	Coverage Δ
integration	62.57% <30.55%> (-0.29%)	⬇️
mongodb	14.12% <0.00%> (-0.08%)	⬇️
pg	52.10% <30.55%> (-0.26%)	⬇️
tigris	33.75% <0.00%> (-0.12%)	⬇️
unit	24.83% <38.88%> (-0.03%)	⬇️

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[w84thesun]

Overall good, except for those comments @AlekSi already provided.

[vercel]

Deployment failed with the following error:

Creating the Deployment Timed Out.

[chilagrow]

Looks good to me 🚀