feat: Set service version on OTel data

[morgan-wowk]

TL;DR

Added service version support to OpenTelemetry configuration and tracing setup.

What changed?

• Added service_version field to OtelConfig dataclass
• Extended resolve() function to accept optional service_version parameter with fallback to TANGLE_SERVICE_VERSION environment variable (defaults to "unknown")
• Updated setup() functions in both providers.py and tracing.py to accept and pass through service_version parameter
• Modified tracing setup to include service.version attribute in OpenTelemetry resource when provided
• Added comprehensive test coverage for service version functionality including custom values, environment variable usage, and default behavior

How to test?

1. Set TANGLE_SERVICE_VERSION environment variable and verify it's picked up by the configuration
2. Pass a custom service_version parameter to providers.setup() and confirm it overrides the environment variable
3. Check that the service.version attribute appears in OpenTelemetry traces when configured (requires OTel collector stack)
4. Verify that when no service version is provided, it defaults to "unknown" and the attribute is omitted from traces when explicitly set to None

Why make this change?

This enables better observability by allowing services to report their version information (such as git commit hashes or release versions) to OpenTelemetry collectors, making it easier to correlate traces with specific deployments and track issues across different service versions.

[morgan-wowk]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: Measure system errors using a counter #127
• feat: Setup metric provider for manual and auto-instrumented measurements #126
• chore!: Refactor OTel exporters to be signal-specific #125
• feat: Set service version on OTel data #124 👈 (View in Graphite)
• chore: Refactor OTel concerns in preparation for metric provider #123
• master

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