[RELEASE] Release opentelemetry-cpp 1.29

[marcalff]

Planned, no estimated date yet.

Must have:

• [CONFIGURATION] Implement ComposableSampler Extensions #4409
• [CONFIGURATION] Complete resource detection support in SdkBuilder #4411
• [CONFIGURATION] Create builders for the container and process resource detectors #4412
• [SDK] Replace SpinLockMutex with std::mutex in the metrics library #4416
• [CONFIGURATION] Set schema default values for all parameters #4432
• [CONFIGURATION] Cleanup build targets and docs #4486
• [CMAKE] Upgrade third-party dependencies for the 1.29.0 release #4506
• [TEST] BasicCurlHttpTests.RepeatedCallerThreadCancelsAreClean is flaky #4510

Desirable:

• [BUILD] Rename cmake options with prefix OTELCPP_  #4268
• [RESOURCE DETECTOR] Host resource detector #4413
• [RESOURCE DETECTOR] Service resource detector #4414
• [CONFIGURATION] Registry has builders for all components and link only what you use #4352
• [CONFIGURATION/BUILD] Resource detector targets and README #4430
• [CONFIGURATION] deprecate builder cmake components #4428
• [CONFIGURATION] Support environment variable substitution for attributes #4474
• [RESOURCE] Process resource detector reports more attributes #4437
• [CONFIGURATION] Apply general attribute_limits to tracer and logger providers #4468
• [CONFIGURATION] Internal logging cleanup #4479
• [TEST] Code cleanup in exporter tests #4158

Deferred:

• Define and enforce a runtime minimum scale for Base2ExponentialHistogramAggregation #4325

[dbarker]

Must have:

• [CONFIGURATION] Complete resource detection support in SdkBuilder #4411
• [CONFIGURATION] Create builders for the container and process resource detectors #4412
• [SDK] Replace SpinLockMutex with std::mutex in the metrics library #4416
• Define and enforce a runtime minimum scale for Base2ExponentialHistogramAggregation #4325
• [CONFIGURATION] Set schema default values for all parameters #4432

Desirable:

• [BUILD] Rename cmake options with prefix OTELCPP_  #4268
• [RESOURCE DETECTOR] Host resource detector #4413
• [RESOURCE DETECTOR] Service resource detector #4414
• [CONFIGURATION] Registry has builders for all components and link only what you use #4352
• [CONFIGURATION/BUILD] Resource detector targets and README #4430
• [CONFIGURATION] deprecate builder cmake components #4428