[CONFIGURATION] File configuration - configuration parser

[marcalff]

Contributes to #2481

This is a partial fix, that implements the configuration parser.

Changes

Please provide a brief description of the changes here.

• Implement the configuration parser.

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

[netlify]

✅ Deploy Preview for opentelemetry-cpp-api-docs canceled.

Name	Link
🔨 Latest commit	2de3749
🔍 Latest deploy log	https://app.netlify.com/projects/opentelemetry-cpp-api-docs/deploys/6870d620d8d8bc0008650a14

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.97%. Comparing base (7a78dd0) to head (2de3749).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3520      +/-   ##
==========================================
- Coverage   89.98%   89.97%   -0.01%     
==========================================
  Files         219      219              
  Lines        7044     7044              
==========================================
- Hits         6338     6337       -1     
- Misses        706      707       +1     

see 1 file with indirect coverage changes

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[dbarker]

LGTM. Thanks!