Populate the view of local aliases from the new API rather than m.room.aliases

[jryans]

As an urgent subset of MSC2432, we should change to using the new API GET /_matrix/client/r0/rooms/{roomId}/aliases instead of m.room.aliases when showing local aliases.

Additional info on alias changes

[bwindels]

working on editing alt_aliases on branch bwindels/altaliases