[improve][pip] PIP-320: OpenTelemetry Scaffolding

[asafm]

Motivation

Adding PIP-320, which a sub-PIP of PIP-264 (Implementation tracked at #21121).
This PIP is about adding the infrastructure to use OpenTelemetry in Pulsar broker, proxy and function worker.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[github-actions]

@asafm Please add the following content to your PR description and select a checkbox:

- [ ] `doc` <!-- Your PR contains doc changes -->
- [ ] `doc-required` <!-- Your PR changes impact docs and you will update later -->
- [ ] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->

[visortelle]

I left some comments. Asked questions I was interested in during the reading.
Don't consider it a review. I’m not deep enough into the metrics/OTel topic to leave comments that may be considered as a review.

[Apurva007]

A few small clarifications needed. Overall looks good.

[BewareMyPower]

LGTM

[Apurva007]

LGTM

[asafm]

@lhotari The vote has been concluded and approved. Can you merge it?