Add remove property functions

[lovrogalesic-toast]

Fixes #855

Motivation

This PR adds the ability to unset some namespace properties instead of always setting them to the value of 0. The goal is to unset the properties when they are removed from the terraform declarations when using terraform-provider-pulsar

Modifications

• added remove property functions
• updated get functions for the same properties to handle the new values (-1 for unset, 0 is zero...)
• some status message updates (wording)

Verifying this change

• [ ] Make sure that the change passes the CI checks.

Tests to add:

• Property removal tests

Documentation

Check the box below.

Need to update docs?

• [x] doc-required

These changes should be documented and explained as they might be breaking for some users.

[nodece]

@lovrogalesic-toast Could you check the failed CI?