Add Prohibited Domains list to Admin UI

[miketheman]

Now that we not only rely on the disposable-email-domains, and have our own domain blocklist (see #15672) we should be able to display these and manage them in the Admin UI.

We likely need:

• new routes to display paginated entries, update/remove entries
• html templates
• a search function - or at least a DataTables setting

[samjove]

Would this be similar to what exists for prohibited project names?

[miketheman]

Would this be similar to what exists for prohibited project names?

Yes, that's the general idea.

[samjove]

Great I'll work on this

[miketheman]

@samjove any progress? If not, that's okay! I'll be looking to start on this tomorrow, since I'm finding the need to get this done sooner.