feat(breadcrumbs): add _meta information for truncation of breadcrumbs

[shellmayr]

• Implements annotations for breadcrumbs

• Adds an int field to Scope to track the number of truncated breadcrumbs

• When scopes are merged, the number of breadcrumbs that were removed are added

• If breadcrumbs were truncated, add the original number of breadcrumbs to _meta

• Closes https://github.com/getsentry/projects/issues/593

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 79.56%. Comparing base (5f71872) to head (e9a5e51).
Report is 4 commits behind head on master.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/scope.py	87.50%	0 Missing and 2 partials ⚠️
sentry_sdk/scrubber.py	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4007      +/-   ##
==========================================
+ Coverage   79.51%   79.56%   +0.04%     
==========================================
  Files         142      142              
  Lines       15876    15894      +18     
  Branches     2716     2721       +5     
==========================================
+ Hits        12624    12646      +22     
+ Misses       2388     2381       -7     
- Partials      864      867       +3     

Files with missing lines	Coverage Δ
sentry_sdk/client.py	79.05% <100.00%> (+0.29%)	⬆️
sentry_sdk/scrubber.py	94.44% <0.00%> (ø)
sentry_sdk/scope.py	86.08% <87.50%> (-0.07%)	⬇️

... and 3 files with indirect coverage changes

[szokeasaurusrex]

@cleptric given that we want to move towards not truncating any data in SDKs, should we still be implementing this change?

[antonpirker]

I have a question

[antonpirker]

This looks good now! @shellmayr please fix the linting errors so this can be merged.