feat(spans): track and report spans that were dropped

[constantinius]

_SpanRecorder now keeps track of dropped_spans, i.e. when above max_spans.

When spans were dropped, the "spans" property will be wrapped in an AnnotatedValue, reporting the mutation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.23%. Comparing base (2724d65) to head (66b50f8).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4005      +/-   ##
==========================================
+ Coverage   80.15%   80.23%   +0.07%     
==========================================
  Files         139      139              
  Lines       15403    15388      -15     
  Branches     2597     2597              
==========================================
- Hits        12347    12346       -1     
+ Misses       2211     2198      -13     
+ Partials      845      844       -1     

Files with missing lines	Coverage Δ
sentry_sdk/client.py	79.01% <100.00%> (+0.41%)	⬆️
sentry_sdk/scrubber.py	94.44% <100.00%> (+1.29%)	⬆️
sentry_sdk/tracing.py	77.84% <100.00%> (+0.27%)	⬆️
sentry_sdk/transport.py	80.43% <100.00%> (+0.38%)	⬆️
sentry_sdk/utils.py	84.01% <100.00%> (+0.30%)	⬆️

... and 2 files with indirect coverage changes

[sentrivana]

Thanks for simplifying! Overall looks good to me, but please address comments before merging

[sentrivana]

Oh yeah, and the CI / Lint Sources step is failing -- should be fixed if you run the codebase through black. (Or pip install pre-commit in the venv where you have the SDK installed and it should run the checks on commit and also reformat.)