[RFC] Poc config yaml

[marcalff]

Fixes #2481

Request For Comments (Proof of concept code for now)

Start with examples/yaml/main.cc

Features implemented:

• https://github.com/open-telemetry/opentelemetry-configuration
  • Full support for propagators
  • Full support for traces, including recursive sampler definitions.
• Extension points
  • Custom propagators
  • Custom samplers
  • Custom span processors
  • Custom span exporters

Changes

Please provide a brief description of the changes here.

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

All modified and coverable lines are covered by tests ✅

Project coverage is 87.54%. Comparing base (497eaf4) to head (4bb5fe4).
Report is 61 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2518      +/-   ##
==========================================
+ Coverage   87.12%   87.54%   +0.42%     
==========================================
  Files         200      188      -12     
  Lines        6109     5840     -269     
==========================================
- Hits         5322     5112     -210     
+ Misses        787      728      -59     

see 64 files with indirect coverage changes