[Remotes] Add endpoint to update server connection

[thomtrp]

What

Server connection should be editable. We need to add a new endpoint. See how this is done to remove a server.

How

• Rename CreateRemoteServerInput into RemoteServerInput
• Input { id: <string>, server: RemoteServerInput }
• Unsync existing foreign tables as it is done during deletion
• alter foreign data wrapper https://www.postgresql.org/docs/current/sql-alterforeigndatawrapper.html
• alter user mapping https://www.postgresql.org/docs/current/sql-alterusermapping.html