SOLR-16390: Tweak clusterprop APIs to be more REST-ful

[gerlowskija]

https://issues.apache.org/jira/browse/SOLR-16390

Description

Solr has slowly been modifying its v2 APIs to align around a more REST-ful model. Many APIs have already been through this re-alignment but many more remain, including a handful of "collection-admin" APIs.

Solution

This PR chips away at this gap by tweaking Solr's "clusterprop" APIs to be more REST-ful:

• single property creation+update is now available at PUT /api/cluster/properties/propName {...}
• bulk property creation+update is now available at PUT /api/cluster/properties {...}
• single property deletion is now available at DELETE /api/cluster/properties/propName

Tests

TODO

Checklist

Please review the following and check all that apply:

• [x] I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• [x] I have created a Jira issue and added the issue ID to my pull request title.
• [x] I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• [x] I have developed this patch against the main branch.
• [ ] I have run ./gradlew check.
• [ ] I have added tests for my changes.
• [ ] I have added documentation for the Reference Guide