[improve][pip] PIP-347: add role field in consumer's stat

[thetumbled]

Motivation

By setting config allowAutoSubscriptionCreation=true, we allow user to create subscriptions automatically if user have the consume permission.
We have a strong need to trace back the owner of a specific subscription, but currently there is no such way to achieve that.

Modifications

Add field role in the stats response.

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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

Matching PR in forked repository

PR in forked repository: thetumbled#48

[thetumbled]

PTAL, thanks. @lhotari @codelipenghui @BewareMyPower @Technoboy- @dao-jun @poorbarcode

[BewareMyPower]

Since this PR adds a new method to an existing public interface in the pulsar-xxx-api module, it needs a PIP.

We have a strong need to trace back the owner of a specific subscription

It's better to explain a bit more for why the role is needed here. From the wiki of statistics

Statistics (from German: Statistik, orig. "description of a state, a country")[1][2] is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data.

The role info is more like an attribute of a consumer, not a statistics. Generally, the role info never changes unlike other fields (e.g. the in/out rate)

[thetumbled]

this is the pip for this pr: #22564.