Rebase the cursor after focusing in a direction

Prior to this patch, creating a tabbed container with two views,
switching tab and then scrolling without motion would cause the scroll
events to be sent to the old focus. To fix this, rebasing the cursor is
needed after changing focus.

sway/commands/focus.c

@@ -294,6 +294,7 @@ struct cmd_results *cmd_focus(int argc, char **argv) {
 	if (next_focus) {
 		seat_set_focus(seat, next_focus);
 		seat_consider_warp_to_focus(seat);
+		cursor_rebase(seat->cursor);
 	}
 
 	return cmd_results_new(CMD_SUCCESS, NULL, NULL);