Recalculate tiling layout on change of display configuration

Previously, changing the resolution, scale, or orientation of a display
left tiling layouts that don't fill the screen and/or extend off of the
screen area, until an action like opening a window makes it recalculate
window positions.

Now this is done immediately when the output configuration changes.

Perhaps we should consider if we want a different animation for things
like rotating a screen, but the current behavior isn't too bad.

For floating layouts, `refresh` already remaps windows that are out of
bounds for the output, so this doesn't change that. Perhaps decreasing
the resolution (or moving to a lower resolution output) should try to
reduce the window size. But the current behavior generally seems okay.

src/state.rs

@@ -358,6 +358,9 @@ impl BackendData {
             self.schedule_render(&output);
         }
 
+        // Update layout for changes in resolution, scale, orientation
+        shell.workspaces.recalculate();
+
         loop_handle.insert_idle(|state| state.common.update_xwayland_scale());
 
         Ok(())