[CONFIGURATION] File configuration - prometheus exporter builder

[marcalff]

Contributes to #2481

This is a partial fix, to implement the prometheus exporter builder.

Changes

Please provide a brief description of the changes here.

• Add a new option constructor, that ignores environment variables
• Implement the prometheus exporter builder

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	a377c1c
🔍 Latest deploy log	https://app.netlify.com/projects/opentelemetry-cpp-api-docs/deploys/6886c2476e29e50008a19827

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.02%. Comparing base (59e7281) to head (a377c1c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3564      +/-   ##
==========================================
- Coverage   90.03%   90.02%   -0.01%     
==========================================
  Files         220      220              
  Lines        7069     7069              
==========================================
- Hits         6364     6363       -1     
- Misses        705      706       +1     

see 1 file with indirect coverage changes

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[dbarker]

Looks good. Thanks! - minor nitpick on potential to use rule of zero.