Add fields to listCollections.cursor response

[henvic]

Description

Add extra fields to ListCollections.cursor.

Closes #2815.

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 #3809 (21cdc73) into main (13d2680) will decrease coverage by 0.50%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3809      +/-   ##
==========================================
- Coverage   76.66%   76.17%   -0.50%     
==========================================
  Files         316      316              
  Lines       23635    23655      +20     
==========================================
- Hits        18120    18019     -101     
- Misses       4472     4589     +117     
- Partials     1043     1047       +4     

Files	Coverage Δ
internal/handler/msg_listcollections.go	73.00% <100.00%> (+6.75%)	⬆️

... and 17 files with indirect coverage changes

Flag	Coverage Δ
filter-false	?
filter-true	72.32% <100.00%> (-0.29%)	⬇️
hana-1	?
integration	72.32% <100.00%> (-0.53%)	⬇️
mongodb-1	5.18% <0.00%> (-0.01%)	⬇️
mysql-1	?
mysql-2	?
mysql-3	?
postgresql-1	51.99% <100.00%> (-0.47%)	⬇️
postgresql-2	52.26% <59.09%> (+0.72%)	⬆️
postgresql-3	52.14% <59.09%> (-0.49%)	⬇️
sqlite-1	51.20% <100.00%> (-0.50%)	⬇️
sqlite-2	51.39% <59.09%> (+0.57%)	⬆️
sqlite-3	51.25% <59.09%> (-0.52%)	⬇️
unit	30.65% <0.00%> (-0.03%)	⬇️

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

[AlekSi]

No backend changes are needed in this issue/PR

[AlekSi]

(for maintainers only) I set Reviewers (@FerretDB/core), Milestone (Next), Labels, Project and project's Sprint fields.

@henvic the maintainer is you. Please do that in the next PR.

I marked all done items in this checklist.

Please also do that.

[rumyantseva]

It's strange that codecov shows the lines uncovered, but the implementation and the test look good to me.