Add export traces to gcs

[gafda]

This pull request adds support for exporting traces, in addition to logs, to Google Cloud Storage in the googlecloudstorageexporter. It updates the configuration, implementation, and tests to handle traces, and improves how encoding extensions are loaded for both logs and traces.

Traces Export Support:

• Added support for exporting traces alongside logs, including implementation of ConsumeTraces, trace marshaling, and registration of the traces exporter. [1] [2] [3] [4] [5]

Configuration and Documentation Updates:

• Updated the README.md and metadata.yaml to reflect support for traces and clarify how the encoding option works for both logs and traces. [1] [2] [3]

Configuration Handling Improvements:

• Changed the Encoding field in the config struct from a pointer to a value, simplifying usage and reducing nil checks. [1] [2]

Testing Enhancements:

• Added and updated tests to cover traces export, including new mock marshalers for traces and both signals, and additional test cases for encoding extension scenarios. [1] [2] [3] [4] [5] [6]

Configuration Example:

exporters:
  # ...
  googlecloudstorage/traces:
    # ...
    bucket:
      name: "YOUR_BUCKET_NAME"
      project_id: "YOUR_GCP_PROJECT_ID"
      region: "YOUR_BUCKET_REGION"
      # ...

  googlecloudstorage/logs:
    # ...
    bucket:
      name: "YOUR_BUCKET_NAME"
      project_id: "YOUR_GCP_PROJECT_ID"
      region: "YOUR_BUCKET_REGION"
      # ...

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Copilot / name: copilot-swe-agent[bot] (0acea5d, b35f117, b529236)
• ✅ login: gafda / name: Gil Assunção (18ace46, 2e9f4a0, 37fe601, 401ad8d, 6a50407, ba9464d, c471a64)

[github-actions]

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[constanca-m]

Thanks for the contribution Gil, usually it is best to start with opening an issue instead of opening the PR already, just to make sure we can have agreement before implementation.

The PR looks good in general, just a couple of concerns

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[gafda]

@constanca-m, I'm sorry I took too long to fix your review comments. I've been sick for a while.
Hope everything is in order now.

[constanca-m]

Thanks, almost there

[gafda]

I've also rebased this branch with the latest commits from the main branch.

[constanca-m]

Thanks @gafda, looks good

[constanca-m]

@gafda You need to fix the lint errors for the PR to get merged

[gafda]

@constanca-m This branch is now up-to-date with main after a rebase. I've also run make golint and resolved all reported issues. The updated code has been pushed.

[otelbot]

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