feat(boto3): Add ServiceExtension class

[pabloDeputter]

Description

Adds service-extension support to Boto3Integration. This keeps the generic Boto3 call lifecycle independent of individual AWS services.

• Adds _ServiceExtension interface for service-specific behavior through _get_span_config(), _get_request_attributes(), and _get_response_attributes(). This allows for custom span operations/origin, request attributes, and response/error attributes. A future method can also inject trace context into service-specific payload, e.g. SQS message attributes.
• Extensions are lazily imported (not sure whether this actually a good thing). Service modules are only imported on first use and falls back to generic behavior when service is unknown or broken.
• Generic attributes and errors remain authoritative over service-specific ones.

Issues

Resolves #7477

[github-actions]

Codecov Results 📊

✅ 130421 passed | ⏭️ 7171 skipped | Total: 137592 | Pass Rate: 94.79% | Execution Time: 445m 23s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +1066
Passed Tests	📈 +1043
Failed Tests	—
Skipped Tests	📈 +23

All tests are passing successfully.

✅ Patch coverage is 84.75%. Project has 2566 uncovered lines.
✅ Project coverage is 90.25%. Comparing base (a72a791) to head (17d48a0).

Files with missing lines (3)

File	Patch %	Lines
sentry_sdk/integrations/boto3/_services/registry.py	61.11%	⚠️ 7 Missing and 1 partials
sentry_sdk/integrations/boto3/_instrumentation.py	92.86%	⚠️ 1 Missing and 2 partials
sentry_sdk/integrations/boto3/_services/base.py	88.89%	⚠️ 1 Missing

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
+ Coverage    90.20%    90.25%    +0.05%
==========================================
  Files          194       201        +7
  Lines        25888     26320      +432
  Branches      9584      9752      +168
==========================================
+ Hits         23352     23754      +402
- Misses        2536      2566       +30
- Partials      1455      1462        +7

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Generated by Codecov Action

[sentry-warden]

Custom service origin skips streamed request enrichment

When a service extension overrides span origin, streamed spans fail the origin check in _sentry_request_created, so request attributes and _sentrysdk_span are never attached. Please keep the boto3 origin (or update that guard) if origin overrides are supported.

Evidence

• In _start_client_span, a non-empty service_origin from service_ext.get_span_config(ctx) replaces span_origin and is written to SPANDATA.SENTRY_ORIGIN for streamed spans.
• _sentry_request_created returns early when the current span is a StreamedSpan whose SPANDATA.SENTRY_ORIGIN is not exactly Boto3Integration.origin.
• That early return skips _set_request_attributes() and never sets request.context["_sentrysdk_span"].
• test_service_extension_customizes_client_span only overrides op (("aws.test", None)), so this origin path is untested.

Also found at 1 additional location

• sentry_sdk/integrations/boto3/_client.py:92-92

_{Identified by Warden · code-review, find-bugs · JFX-TK2}