Correctly migrate duplicate clusters in workspaces (#3211)

- Keep track of the set of all workspaces that each duplicated entry was
  a part of

Signed-off-by: Sebastian Malton <sebastian@malton.name>

src/common/cluster-store.ts

@@ -71,6 +71,11 @@ export interface ClusterModel {
    */
   workspace?: string;
 
+  /**
+   * @deprecated this is used only for hotbar migrations from 4.2.X
+   */
+  workspaces?: string[];
+
   /** User context in kubeconfig  */
   contextName: string;