Support custom properties for Tenants and Namespaces

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Motivation

In Pulsar 2.11 we can store custom properties in Topics and in Subscription.
We lack the ability to tag Tenants and Namespaces with custom properties.

### Solution

Support setting a custom set of key-value pairs on Tenants and on Namespaces.

The map can be immutable

### Alternatives

_No response_

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start by examining the existing custom-property support for topics and subscriptions, then trace how tenant and namespace settings are exposed and persisted. The work is done when both tenants and namespaces support setting key-value custom properties, including an immutable map if appropriate, with coverage for the new behavior.

Written by the indexing model from the issue text.