xwayland: connect commit and surface_destroy handlers together

Factor out set_surface() which consolidates connecting/disconnecting
the wlr_surface event listeners in one place.

In theory, this means we can receive commit events for minimized views.
However, with a test app that resizes itself, I didn't see any change,
i.e. the commits still don't come through until un-minimize. It's
possible they are being filtered at wlroots or protocol level.

Also remove an old, semi-related TODO from view.c.

src/view.c

@@ -2479,11 +2479,6 @@ handle_unmap(struct wl_listener *listener, void *data)
 	view->impl->unmap(view, /* client_request */ true);
 }
 
-/*
- * TODO: after the release of wlroots 0.17, consider incorporating this
- * function into a more general view_set_surface() function, which could
- * connect other surface event handlers (like commit) as well.
- */
 void
 view_connect_map(struct view *view, struct wlr_surface *surface)
 {