[otlp] OTLP Exporter Custom serializer Part 2 - Resources

[rajkumar-rangaraj]

Fixes Part of #5730, Follow up #5910
Design discussion issue #

Changes

Please provide a brief description of the changes here.

• Added custom serialization for the OTLP Resource part.
• Updated the tests to deserialize the bytes and validate them against the content generated from Google Protobuf.

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)

[codecov]

Codecov Report

Attention: Patch coverage is 77.47748% with 25 lines in your changes missing coverage. Please review.

Project coverage is 86.30%. Comparing base (6250307) to head (18be666).
Report is 359 commits behind head on main.

Files with missing lines	Patch %	Lines
...ol/Implementation/Serializer/ProtobufSerializer.cs	22.72%	17 Missing ⚠️
...ation/Serializer/ProtobufOtlpResourceSerializer.cs	88.23%	4 Missing ⚠️
...Implementation/Serializer/ProtobufOtlpTagWriter.cs	92.72%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5916      +/-   ##
==========================================
+ Coverage   83.38%   86.30%   +2.91%     
==========================================
  Files         297      260      -37     
  Lines       12531    11456    -1075     
==========================================
- Hits        10449     9887     -562     
+ Misses       2082     1569     -513     

Flag	Coverage Δ
unittests	?
unittests-Project-Experimental	86.17% <77.47%> (?)
unittests-Project-Stable	86.27% <77.47%> (?)

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

Files with missing lines	Coverage Δ
...ation/Serializer/ProtobufOtlpResourceSerializer.cs	88.23% <88.23%> (ø)
...Implementation/Serializer/ProtobufOtlpTagWriter.cs	92.72% <92.72%> (ø)
...ol/Implementation/Serializer/ProtobufSerializer.cs	85.21% <22.72%> (ø)

... and 237 files with indirect coverage changes

[CodeBlanch]

LGTM