Support showRecordId in find

[chilagrow]

Description

Closes #3467.

Also renames enable sort pushdown to unsafe sort pushdown and limit pushdown to unsafe limit pushdown.

Readiness checklist

• I added/updated unit tests (and they pass).
• I added/updated integration/compatibility tests (and they pass).
• I added/updated comments and checked rendering.
• I made spot refactorings.
• I updated user documentation.
• I ran task all, and it passed.
• I ensured that PR title is good enough for the changelog.
• (for maintainers only) I set Reviewers (@FerretDB/core), Milestone (Next), Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[codecov]

Codecov Report

Merging #3637 (d835b19) into main (b31b8e2) will decrease coverage by 0.65%.
The diff coverage is 88.33%.

@@            Coverage Diff             @@
##             main    #3637      +/-   ##
==========================================
- Coverage   76.88%   76.23%   -0.65%     
==========================================
  Files         321      321              
  Lines       22950    22958       +8     
==========================================
- Hits        17644    17502     -142     
- Misses       4290     4423     +133     
- Partials     1016     1033      +17     

Files	Coverage Δ
integration/setup/listener.go	80.44% <100.00%> (-2.23%)	⬇️
integration/setup/setup.go	79.77% <ø> (ø)
integration/setup/test_helpers.go	80.00% <100.00%> (ø)
internal/backends/collection.go	100.00% <ø> (ø)
internal/backends/postgresql/collection.go	71.35% <100.00%> (ø)
internal/backends/sqlite/collection.go	80.15% <100.00%> (-0.80%)	⬇️
internal/clientconn/cursor/cursor.go	100.00% <100.00%> (ø)
internal/clientconn/cursor/registry.go	91.66% <100.00%> (ø)
internal/handlers/common/find.go	100.00% <ø> (ø)
internal/handlers/common/getmore.go	92.76% <100.00%> (+0.09%)	⬆️
... and 10 more

... and 9 files with indirect coverage changes

Flag	Coverage Δ
filter-false	?
filter-true	72.25% <88.33%> (-0.60%)	⬇️
hana-1	?
integration	72.25% <88.33%> (-0.67%)	⬇️
mongodb-1	5.43% <0.00%> (-0.01%)	⬇️
postgresql-1	52.55% <65.00%> (-0.20%)	⬇️
postgresql-2	50.42% <60.00%> (-1.56%)	⬇️
postgresql-3	51.68% <60.00%> (+0.84%)	⬆️
sort-false	72.25% <88.33%> (-0.20%)	⬇️
sort-true	?
sqlite-1	51.86% <73.33%> (-0.43%)	⬇️
sqlite-2	49.74% <68.33%> (-1.49%)	⬇️
sqlite-3	50.84% <68.33%> (+0.81%)	⬆️
unit	29.86% <19.60%> (-0.09%)	⬇️

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

[noisersup]

LGTM

[mergify]

@chilagrow this pull request has merge conflicts.

[noisersup]

Looks good to me! Waiting for other reviews :)

[rumyantseva]

LGTM.