[CONFIGURATION] Implement declarative configuration (config.yaml)

[marcalff]

Fixes #2481

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
  • Custom pull metric exporters
  • Custom push metric exporters
  • Custom log record processors
  • Custom log record 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 89.95%. Comparing base (6673570) to head (402d44d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2518      +/-   ##
==========================================
+ Coverage   89.94%   89.95%   +0.02%     
==========================================
  Files         225      225              
  Lines        7273     7273              
==========================================
+ Hits         6541     6542       +1     
+ Misses        732      731       -1     

see 1 file with indirect coverage changes

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