[PROFILING] Add profiling in opentelemetry-cpp

[marcalff]

Project tracking for SIG C++.

Related:

• Propose OpenTelemetry Profiling Vision oteps#212
• Project Tracking: Profiling opentelemetry-specification#2731

[github-actions]

This issue was marked as stale due to lack of activity.

[brancz]

Otlp-Profiling is now in alpha, and we'd like to see SDKs implement support for it, especially for things that the opentelemetry-ebpf-profiler cannot profile or only with very high overhead, such as heap profiling data.

Bonus for supporting process context and thread context when they're ready.

The profiling working group would welcome questions or input, and feel free to join the fortnightly call. All information about the call is at the top of our running meeting notes.