Role Assignment for SOLR Replicas

Hi Team!

I was wondering if we have possibility to assign different roles for replicas, each of which is essentially a SOLR node, using SOLR's [Node Roles](https://solr.apache.org/guide/solr/latest/deployment-guide/node-roles.html) feature?

Start with the Apache Solr Node Roles documentation linked in the issue, then review how this operator represents replicas and their configuration. Define how role assignments would be expressed and applied per replica, and document the tests or observable Solr behavior that would establish completion.

Written by the indexing model from the issue text.