[CONFIGURATION] Complete resource detection support in SdkBuilder

[mateenali66]

Fixes #4411

Changes

Implements the remaining resource detection support in SdkBuilder::SetResource, per the required behavior on the issue:

• Detector dispatch: a ResourceDetectorBuilder visitor (same pattern as SpanExporterBuilder) resolves container, host, process and service to their registry builders, and any other name to an extension detector builder looked up by name. A missing builder throws UnsupportedException, consistent with the other Create* methods.
• Attribute filter: the merged detected resource is filtered with detection.attributes using sdk::common::WildcardMatch. Absent included passes all keys, excluded is applied after included and wins. The filter applies to detected attributes only.
• Merge priority, lowest first: Resource::GetDefault(), detected resource (filtered), attributes_list, then attributes with schema_url from the model. Merging relies on the documented behavior that the updating resource wins on key conflicts and an empty updating schema url preserves the current one.

Behavior note, called out in the changelog: SetResource no longer goes through Resource::Create(), so it no longer runs OTELResourceDetector (the OTEL_RESOURCE_ATTRIBUTES env var) and no longer injects a default service.name. Neither is part of the configuration model, and Resource::Create() cannot express the required merge order.

The example yaml files listed detectors that nothing registers (they were ignored until now), which the new error behavior turns into SDK build failures. Those entries move to comments until the example registers builders for them; the my_custom_detector entry comes back with #4419 (PR #4423), which registers the extension builder.

Tests cover the dispatch (typed and extension, with a spy builder), the unregistered-detector failure, the filter semantics (wildcard include, excluded-beats-included, default resource untouched), the four-level merge priority on a conflicting key, and the schema url.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

❌ Patch coverage is 70.70707% with 29 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.62%. Comparing base (895f49f) to head (62ff397).

Files with missing lines	Patch %	Lines
sdk/src/configuration/sdk_builder.cc	70.71%	29 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4424      +/-   ##
==========================================
+ Coverage   82.59%   82.62%   +0.04%     
==========================================
  Files         511      511              
  Lines       20039    20132      +93     
==========================================
+ Hits        16550    16633      +83     
- Misses       3489     3499      +10     

Files with missing lines	Coverage Δ
...lude/opentelemetry/sdk/configuration/sdk_builder.h	100.00% <ø> (ø)
sdk/src/configuration/sdk_builder.cc	61.11% <70.71%> (+2.12%)	⬆️

... and 2 files with indirect coverage changes

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[dbarker]

Looks good. Thank you! Please see non blocking feedback below.

[marcalff]

LGTM, thanks for the contribution.