Add protobuf-related utilities

[sfc-gh-gtokernliang]

Description

Add protobuf related utilites.

Other details good to know for developers

Preparation for OTEL span exporting

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• New Tests
• This change includes re-generated golden test results
• This change requires a documentation update

---

Important

Add protobuf utilities for OTEL span exporting, update TruLensDBSpanExporter, and add tests for new utilities.

• Utilities:
  • Add convert_to_any_value and convert_readable_span_to_proto in exporter.py for converting data to protobuf formats.
  • Add check_if_trulens_span and construct_event for span attribute checks and event construction.
• Exporter:
  • Update TruLensDBSpanExporter in exporter.py to use construct_event for event creation.
• Dependencies:
  • Add opentelemetry-proto to Makefile, pyproject.toml, and requirements.txt.
• Tests:
  • Add test_exporter.py to test convert_to_any_value for various data types.

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