workspacesView: Derive workspace state from fit mode

Derive the workspace state WorkspacesView's workspaces from the fit mode.
Extra workspaces still run the zoom animations as before.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1613>

js/ui/workspace.js

@@ -1341,4 +1341,8 @@ class Workspace extends St.Widget {
 
         return false;
     }
+
+    get stateAdjustment() {
+        return this.layout_manager.stateAdjustment;
+    }
 });