Add option for blocks/suspends/quarantines to work on all subdomains

This is something that Mastodon can do now that would be very useful for administration. When a new instance pops up that you'd like to defederate from (for harassment, as an example), taking action doesn't do anything for their subdomains. This means if they have another instance set up on that domain, they can reach you from there. There should be some way to prevent this, either with a wildcard or a setting that makes it so that actions apply to subdomains.