Move view {x,y,width,height} into container struct

This renames/moves the following properties:

* sway_view.{x,y,width,height} ->
sway_container.content_{x,y,width,height}
    * This is required to support placeholder containers as they don't
    have a view.
* sway_container_state.view_{x,y,width,height} ->
sway_container_state.content_{x,y,width,height}
    * To remain consistent with the above.
* sway_container_state.con_{x,y,width,height} ->
sway_container_state.{x,y,width,height}
    * The con prefix was there to give it contrast from the view
    properties, and is no longer useful.

The function container_set_geometry_from_floating_view has also been
renamed to container_set_geometry_from_content.

sway/commands/border.c

@@ -93,7 +93,7 @@ struct cmd_results *cmd_border(int argc, char **argv) {
 	}
 
 	if (container_is_floating(container)) {
-		container_set_geometry_from_floating_view(container);
+		container_set_geometry_from_content(container);
 	}
 
 	arrange_container(container);

sway/commands/resize.c

@@ -404,13 +404,10 @@ static struct cmd_results *resize_adjust_floating(enum resize_axis axis,
 	con->width += grow_width;
 	con->height += grow_height;
 
-	if (con->view) {
-		struct sway_view *view = con->view;
-		view->x += grow_x;
-		view->y += grow_y;
-		view->width += grow_width;
-		view->height += grow_height;
-	}
+	con->content_x += grow_x;
+	con->content_y += grow_y;
+	con->content_width += grow_width;
+	con->content_height += grow_height;
 
 	arrange_container(con);
 
@@ -546,13 +543,10 @@ static struct cmd_results *resize_set_floating(struct sway_container *con,
 		}
 	}
 
-	if (con->view) {
-		struct sway_view *view = con->view;
-		view->x -= grow_width / 2;
-		view->y -= grow_height / 2;
-		view->width += grow_width;
-		view->height += grow_height;
-	}
+	con->content_x -= grow_width / 2;
+	con->content_y -= grow_height / 2;
+	con->content_width += grow_width;
+	con->content_height += grow_height;
 
 	arrange_container(con);