fix: restrict who can remove aliases

Previously, anyone could remove any local alias, meaning that someone could re-route a popular alias elsewhere
Now, only the creator of the alias, users who can set canonical aliases for the room, server admins and the server user can delete aliases

added some additional changes/fixes to adapt to our codebase

Co-authored-by: strawberry <strawberry@puppygock.gay>
Signed-off-by: strawberry <strawberry@puppygock.gay>