Move items-not-found message into Dialog rather than notification
Add a new setMessage()
method to the Dialog class that can be
used to set the items-not-found message or the existing already-linked
message.
To make this all a bit clearer, move most of the dialog layout setup
into the initialize()
method which now creates the message,
fieldset, and sets up the radio button listener. Each part is then
toggled to be hidden until it's actually used (i.e. by either
setItems()
or setMessage()
being called).
Bug: T356836