[CONFIGURATION] Split programmatic and YAML cmake targets

[pranitaurlam]

Fixes #4134

Summary

• Splits opentelemetry_configuration into two CMake targets:
  • opentelemetry_configuration: programmatic configuration only (sdk_builder.cc, configured_sdk.cc, registry.cc, configuration_parser.cc, document_node.cc, composable sampler builders). No ryml dependency. Built unconditionally as part of the SDK.
  • opentelemetry_configuration_yaml: YAML configuration components (yaml_configuration_parser.cc, ryml_document.cc, ryml_document_node.cc) with the ryml::ryml dependency. Gated by WITH_CONFIGURATION.
• Repurposes WITH_CONFIGURATION to gate only the YAML/ryml target.
• Adds a default constructor to Configuration so it can be instantiated programmatically without a Document.
• Updates cmake component names: configuration_yaml replaces configuration for the YAML component; the configuration component is now the programmatic-only piece included in the SDK.

Test plan

• Build without WITH_CONFIGURATION and verify opentelemetry_configuration links successfully without ryml
• Build with WITH_CONFIGURATION=ON and verify both targets build and tests pass
• Verify the example programmatic configuration from the issue compiles against opentelemetry_configuration alone

cc @marcalff @lalitb @dbarker @ThomsonTan

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: pranitaurlam / name: pranitaurlam (eab1f2b)

[pranitaurlam]

Hi @marcalff @lalitb @dbarker @ThomsonTan

I've opened PR #4138 to resolve issue #4134 — splitting the opentelemetry_configuration CMake target into two separate targets so users can use programmatic configuration without pulling in the ryml dependency.

The EasyCLA check has passed. Could one of you please approve the workflow runs so CI can execute? Any feedback on the implementation is also very welcome.

Thank you!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.02%. Comparing base (4352a63) to head (eab1f2b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4138      +/-   ##
==========================================
+ Coverage   82.01%   82.02%   +0.02%     
==========================================
  Files         385      385              
  Lines       16093    16093              
==========================================
+ Hits        13197    13199       +2     
+ Misses       2896     2894       -2     

Files with missing lines	Coverage Δ
...de/opentelemetry/sdk/configuration/configuration.h	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

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