Add accessibility actions to the drag-and-drop locale list

Dragging is not supported neither by TalkBack or the accessibility
framework at the moment. So we need custom actions to be able
to change the order of the locales.

Also, the remove functionality is difficult to discover and use
with TalkBack only, so we are also adding a "remove" action.

It only removes one locale at the time, but most users don't
really add many locales "by mistake", so there is no real need
to delete a lot of locales at once.

Bug: 28173358
Change-Id: I3566304e3d2de87cf9243d7e87631b12d72fc929