feat: add OTEL instrumentation for next-server + OTEL example

[feedthejim]

fix NEXT-479 (link)

content

This PR adds a getTracer API to Next.js that uses the otel/api under the hood to provide Next.js level instrumentation through Open Telemetry.

This also adds an example with-opentelemetry to demonstrate how it can be used, assuming you have a collector.

This allows most notably to have getServerSideProps and fetch calls inside Server Components traced.

details

• we hide most internals spans, if you want to see all of them, use the NEXT_OTEL_VERBOSE=1 env var
• if you want to use this, you'll need to rely on the config.experimental.instrumentationHook config option to initialise OTEL, like in the example

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have a helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• e2e tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have a helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running pnpm build && pnpm lint
• The "examples guidelines" are followed from our contributing doc

[jankaifer]

Just a reminder to update the readme

[feedthejim]

will do in a subsequent pr

[huozhi]

what's the 0.0.1 version for? should we cache it as a property instead call getTracer each time or this is by designed?

[feedthejim]

Not sure if this makes much difference in both ways

[huozhi]

Need to align this file with other pages should either be js or ts