Notify Moonshine About New Instances

[JoelProminic]

@rat-moonshine has been working on Moonshine logic to detect SHI servers. This is working on macOS (on a branch build).

To complement this, I would like to have SHI call Moonshine (and MoonshineDevelopment) to notify it when there are new servers available. This is similar to the messages MSDKI sends to Moonshine, which @rat-moonshine linked here.

I expect this to trigger at least when a server finishes initial provisioning. Moonshine will automatically avoid duplicate entries, so it is not a problem to trigger this in other cases, but I would prefer that the server at least be running when the update is triggered. If this message triggers focus on Moonshine regardless of whether instances are updated, we will need to be more careful about when the messages are sent.

NOTE: the imported "Vagrant Instance" won't work from Moonshine until the user updates their hosts file. Unfortunately, this means that any new servers will automatically fail to connect in Moonshine when the above message triggers. I don't see a better time for us to update this, though, since SHI does not know when the hosts file is updated.