Add LaunchDarkly and OpenFeature integration

[cmanallen]

Adds LaunchDarkly and OpenFeature integration and extends the Scope with a flags property.

As flags are evaluated by an application they are stored within the Sentry SDK (lru cache). When an error occurs we fetch the flags stored in the SDK and serialize them on the event.

[codecov]

Codecov Report

Attention: Patch coverage is 89.52381% with 11 lines in your changes missing coverage. Please review.

Project coverage is 84.33%. Comparing base (d06a189) to head (200917f).
Report is 4 commits behind head on master.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/flag_utils.py	82.60%	4 Missing ⚠️
sentry_sdk/integrations/openfeature.py	84.00%	2 Missing and 2 partials ⚠️
sentry_sdk/integrations/launchdarkly.py	91.17%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3648      +/-   ##
==========================================
+ Coverage   84.29%   84.33%   +0.04%     
==========================================
  Files         133      136       +3     
  Lines       14262    14367     +105     
  Branches     2405     2417      +12     
==========================================
+ Hits        12022    12117      +95     
- Misses       1489     1497       +8     
- Partials      751      753       +2     

Files with missing lines	Coverage Δ
sentry_sdk/_lru_cache.py	100.00% <100.00%> (ø)
sentry_sdk/consts.py	99.51% <ø> (ø)
sentry_sdk/scope.py	88.51% <100.00%> (+0.30%)	⬆️
sentry_sdk/integrations/launchdarkly.py	91.17% <91.17%> (ø)
sentry_sdk/flag_utils.py	82.60% <82.60%> (ø)
sentry_sdk/integrations/openfeature.py	84.00% <84.00%> (ø)

[sentrivana]

Will have a proper look soon -- just two comments regarding tox for now

[antonpirker]

Hey @cmanallen ! This is the best PR I have received ever! Great work.

The integrations should not change the Scope.

I have created an commit on your branch to illustrate how the flags could live on the integration rather than the scope (I hope you don't mind):
430387f

This way all the functionality is contained in the integration.
I also added some tests to show how you can now set the capacity of the buffer when initializing the Integration.

wdyt?

Feel free to make changes to my commit if you want to do things differently.

[cmanallen]

@antonpirker Reverted your commit per our conversation on Slack. Tl;dr the commit didn't work because we need to be tied to the scope to maintain flag isolation. After @sl0thentr0py's comment about it being fine to keep the flags on the scope if this change is permanent I think its appropriate to revert that change.

[antonpirker]

After discussion with the team updating the scope is fine. This is ready to be merged!

[cmanallen]

Thanks @antonpirker and welcome back!