Ability to set custom hostname for SolrCloud

[mcarroll1]

Hello,

Much like the addressability.external.domainName value in the SolrCloud resource, it would be helpful to have something like addressability.external.hostName to specify a particular hostname for external accessibility. It appears now that the hostname is always set to <namespace>-<solrcloud-name>-solrcloud (https://github.com/apache/solr-operator/blob/main/api/v1beta1/solrcloud_types.go#L1339) which is a bit redundant for my team's implementation of one SolrCloud per namespace (we end up with something like solralpha-solralpha-solrcloud.domain.com).

Thanks for your consideration!