feat: escape tag strings

[karel-rehor]

Proposed Changes

Add newline escapes to tag value strings, to be compatible with behavior of earlier client versions.

Also better checks for envars on integration tests.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• Tests pass
• Commit messages are conventional
• Sign CLA (if not already signed)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.32%. Comparing base (ea6f9d2) to head (1eef1a3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #105      +/-   ##
==========================================
+ Coverage   85.28%   85.32%   +0.03%     
==========================================
  Files          14       14              
  Lines        1121     1124       +3     
==========================================
+ Hits          956      959       +3     
  Misses        137      137              
  Partials       28       28              

Flag	Coverage Δ
	85.32% <100.00%> (+0.03%)	⬆️

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[vlastahajek]

Good job.