[feature] Allow non-admin users to view domain blocks/allows via settings panel

[tsmethurst]

Currently it's possible to hide the list of domain blocks from the public, which is handy, but logged-in non-admin users should still be able to see (not edit!) domain permissions in the settings panel, so they can understand if and why a domain was blocked etc.

This should be p. easy to do as the domain blocks GET endpoint already accepts an auth token via the API, so it's just a matter of adding something to the settings panel really.