feat(flags): add Statsig integration

[aliu39]

New integration for tracking Statsig (pypi) flag evaluations, specifically the checkGate method which is used for boolean release flags. Unlike JS, there's no support for event callbacks for Statsig's server SDKs. Instead we wrap the module-level check_gate function.

Ref https://develop.sentry.dev/sdk/expected-features/#feature-flags

Ref

• https://github.com/getsentry/team-replay/issues/538

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
22143	1	22142	5782

View the full list of 1 ❄️ flaky tests

tests.integrations.stdlib.test_httplib test_http_timeout

Flake rate in main: 69.03% (Passed 35 times, Failed 78 times)

Stack Traces | 0.188s run time

.../integrations/stdlib/test_httplib.py:373: in test_http_timeout
    assert len(transaction["spans"]) == 1
E   assert 0 == 1
E    +  where 0 = len([])

To view more test analytics, go to the Test Analytics Dashboard
_{📋 Got 3 mins? Take this short survey to help us improve Test Analytics.}

[cmanallen]

We have a function for this:

sentry-python/sentry_sdk/feature_flags.py

Line 35 in 9ff100a

def add_feature_flag(flag, result):

[cmanallen]

This wasn't an issue in the openfeature integration:

sentry-python/sentry_sdk/integrations/openfeature.py

Lines 6 to 14 in 9ff100a

	try:
	from openfeature import api
	from openfeature.hook import Hook
	if TYPE_CHECKING:
	from openfeature.flag_evaluation import FlagEvaluationDetails
	from openfeature.hook import HookContext, HookHints
	except ImportError:
	raise DidNotEnable("OpenFeature is not installed")