[feat]: Custom Backend Tracing

[oandreeva-nv]

What does the PR do?

Currently Triton Trace capabilities are limited to reporting of a predefined set of activities listed here. Neither of the listed options support tracing a custom activity that a potential user might want to capture.

This PR includes core side adjustments, described in TEP:

• Addition of TRITONSERVER_InferenceTraceReportActivity
• Introduces only 1 type of new activity: TRITONSERVER_TRACE_CUSTOM_ACTIVITY

Sample OpenTelemetry trace:

Checklist

• PR title reflects the change and is of format <commit_type>: <Title>
• Changes are described in the pull request.
• Related issues are referenced.
• Populated github labels field
• Added test plan and verified test passes.
• Verified that the PR passes existing CI.
• Verified copyright is correct on all changed files.
• Added succinct git squash message before merging ref.
• All template sections are filled out.
• Optional: Additional screenshots for behavior/output changes with before/after.

Commit Type:

Check the conventional commit type
box here and add the label to the github PR.

• build
• ci
• docs
• feat
• fix
• perf
• refactor
• revert
• style
• test

Related PRs:

Where should the reviewer start?

Test plan:

Tested with identity backend in server PR: triton-inference-server/server#7403
identity backend: triton-inference-server/identity_backend#30

• CI Pipeline ID: 16268312

Caveats:

Background

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• closes GitHub issue: #5777