ref: Cleanup outgoing propagation_context logic

[sl0thentr0py]

Description

• Add get_baggage, get_traceparent and iter_headers to PropagationContext so that the contract is similar to Span.
  • This clarifies that the PropagationContext and Span are themselves responsible for constructing these values and not the Scope.
  • Currently, it is all a mess on Scope which does not clarify state responsibilities correctly on who holds and can populate what.
• Add Baggage.populate_from_propagation_context as a replacement for Baggage.from_options (that took a scope argument).
• Unify all the various propagation_context presence checks in Scope methods to get_active_propagation_context.
  • This get_active_propagation_context logic then remains the central problem to fix in the future.

Deprecations

The following methods are thus no longer used internally and deprecated.

• Scope.get_dynamic_sampling_context
• Scope.iter_headers
• Baggage.from_options

[codecov]

Codecov Report

❌ Patch coverage is 72.72727% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.23%. Comparing base (2ce4379) to head (1ac88a0).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/scope.py	57.14%	3 Missing and 3 partials ⚠️
sentry_sdk/tracing_utils.py	84.21%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5215      +/-   ##
==========================================
- Coverage   84.25%   84.23%   -0.02%     
==========================================
  Files         181      181              
  Lines       18463    18458       -5     
  Branches     3288     3282       -6     
==========================================
- Hits        15556    15549       -7     
- Misses       1894     1902       +8     
+ Partials     1013     1007       -6     

Files with missing lines	Coverage Δ
sentry_sdk/tracing_utils.py	86.79% <84.21%> (-0.03%)	⬇️
sentry_sdk/scope.py	88.06% <57.14%> (-0.31%)	⬇️

[sl0thentr0py]

follow up PR
#5217

[sentrivana]

Two small comments re naming for now, will still review properly, need to understand the new flow

[sentrivana]

Same nit as above

Suggested change

	def get_baggage(self):
	def to_baggage(self):

[sl0thentr0py]

we actually don't use Span.to_baggage anywhere and the Span.iter_headers uses get_baggage from the transaction itself so I'll leave this as get_baggage.

[sentrivana]

Much, much better already, thank you!