Handle findAndModify and update correctly when collection doesn't exist

[noisersup]

Description

This PR closes #651.

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.
• (for maintainers only) I set Reviewers (@FerretDB/core), Assignee, Labels, Project and project's Sprint fields.
• I marked all done items in this checklist.

[codecov]

Codecov Report

Merging #1087 (ab0ea25) into main (9d99140) will increase coverage by 0.15%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1087      +/-   ##
==========================================
+ Coverage   65.57%   65.72%   +0.15%     
==========================================
  Files         248      248              
  Lines       11816    11817       +1     
==========================================
+ Hits         7748     7767      +19     
+ Misses       3198     3182      -16     
+ Partials      870      868       -2     

Impacted Files	Coverage Δ
internal/handlers/pg/msg_findandmodify.go	72.90% <100.00%> (+0.09%)	⬆️
internal/util/version/version.go	55.00% <0.00%> (-5.00%)	⬇️
internal/handlers/common/filter.go	85.38% <0.00%> (ø)
internal/wire/msg_body.go	38.09% <0.00%> (+1.58%)	⬆️
internal/wire/msg_header.go	71.42% <0.00%> (+2.38%)	⬆️
internal/handlers/tigris/msg_update.go	46.71% <0.00%> (+2.63%)	⬆️
internal/clientconn/listener.go	79.16% <0.00%> (+3.12%)	⬆️
internal/handlers/pg/msg_update.go	54.06% <0.00%> (+3.48%)	⬆️
internal/handlers/pg/pgdb/settings.go	44.18% <0.00%> (+4.65%)	⬆️

Flag	Coverage Δ
integration	61.96% <100.00%> (+0.28%)	⬆️
mongodb	18.38% <0.00%> (-0.06%)	⬇️
pg	63.91% <100.00%> (+0.42%)	⬆️
tigris	31.86% <0.00%> (+<0.01%)	⬆️
unit	24.65% <0.00%> (-0.03%)	⬇️

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

[rumyantseva]

As our idea was to understand how mongo behaves and offer the same behavior, this looks good enough to me.

[w84thesun]

LGTM