[otlp] Add Log and Mertic Exporter to transmit custom serialized data

[rajkumar-rangaraj]

Follow up #5969
Design discussion issue #

Changes

Please provide a brief description of the changes here.
Added ProtobufOtlpLogExporter and ProtobufOtlpMetricExporter, which will replace the current OTLP log and metric exporter later.

Next Steps

• Implement retry and run benchmarks

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[CodeBlanch]

LGTM

[codecov]

Codecov Report

Attention: Patch coverage is 13.18681% with 79 lines in your changes missing coverage. Please review.

Project coverage is 84.57%. Comparing base (6250307) to head (2424417).
Report is 392 commits behind head on main.

Files with missing lines	Patch %	Lines
...r.OpenTelemetryProtocol/ProtobufOtlpLogExporter.cs	0.00%	40 Missing ⚠️
...penTelemetryProtocol/ProtobufOtlpMetricExporter.cs	0.00%	37 Missing ⚠️
...lemetryProtocol/OtlpLogExporterHelperExtensions.cs	66.66%	1 Missing ⚠️
...nTelemetryProtocol/OtlpMetricExporterExtensions.cs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5977      +/-   ##
==========================================
+ Coverage   83.38%   84.57%   +1.18%     
==========================================
  Files         297      271      -26     
  Lines       12531    12355     -176     
==========================================
  Hits        10449    10449              
+ Misses       2082     1906     -176     

Flag	Coverage Δ
unittests	?
unittests-Project-Experimental	84.52% <13.18%> (?)
unittests-Project-Stable	84.57% <13.18%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ementation/Serializer/ProtobufOtlpLogSerializer.cs	98.30% <100.00%> (ø)
...ntation/Serializer/ProtobufOtlpMetricSerializer.cs	99.15% <100.00%> (ø)
...lemetryProtocol/OtlpLogExporterHelperExtensions.cs	93.58% <66.66%> (+22.52%)	⬆️
...nTelemetryProtocol/OtlpMetricExporterExtensions.cs	95.45% <66.66%> (-3.56%)	⬇️
...penTelemetryProtocol/ProtobufOtlpMetricExporter.cs	0.00% <0.00%> (ø)
...r.OpenTelemetryProtocol/ProtobufOtlpLogExporter.cs	0.00% <0.00%> (ø)

... and 240 files with indirect coverage changes