NIFI-13873: Showing the spinner on the dialog buttons of Import From Registry. (#9391)

This closes #9391

nifi-frontend/src/main/frontend/apps/nifi/src/app/pages/flow-designer/state/flow/flow.reducer.ts

@@ -39,6 +39,7 @@ import {
     flowSnackbarError,
     groupComponents,
     groupComponentsSuccess,
+    importFromRegistry,
     loadChildProcessGroupSuccess,
     loadConnectionSuccess,
     loadInputPortSuccess,
@@ -380,6 +381,7 @@ export const flowReducer = createReducer(
         createPort,
         createFunnel,
         createLabel,
+        importFromRegistry,
         (state) => ({
             ...state,
             saving: true