NIFI-15825: Adding support for controller services and queue operations in the connector canvas

[mcgilman]

Summary

Adds support for working with controller services and performing queue operations from the connector canvas in the NiFi UI. Promotes the empty-queue NgRx state slice to a location shared by the flow designer and the connector canvas so both surfaces drive the same drop-request flow.

Changes

Connector canvas — context menu

• Canvas-background menu gains Controller Services, Empty All Queues, Drain, and Cancel Drain (alongside the existing Refresh and Leave Group).
• Component menu gains Controller Services and Empty All Queues for process groups, and List Queue and Empty Queue for connections.
• Icons aligned with the flow designer (e.g. fa fa-list for Controller Services).
• Drain and Cancel Drain are gated on connector permissions and the runtime's allowedActions set, and disable while the connector is being saved.

Controller services view (read-only)

• New ConnectorControllerServicesComponent rooted at /connectors/{connectorId}/canvas/{processGroupId}/controller-services, deep-linkable to a specific service.
• Reuses the shared controller-service-table. To support a read-only entry point without mutating entity permissions:
  • Added a readOnly input on controller-service-table that gates the row action menu down to View Configuration, View State, and View Documentation.
  • Added a readonly?: boolean flag on EditControllerServiceDialogRequest. When set, EditControllerService enters view-only mode regardless of the user's permissions or the service's run status.
• New NgRx slice (connector-controller-services — actions, reducer, effects, selectors) handles loading, selection, and dialog wiring.
• Navigation is dispatched as navigateToControllerServices({ processGroupId }) and uses BackNavigation to return to the originating canvas.

Queue operations — shared empty-queue state

• Promoted the previous flow-designer/state/queue slice to state/empty-queue. The flow designer and the connector canvas now dispatch the same actions through a single shared slice.
• A new queueEmptied action carries a CanvasActionSource so each surface filters on the source and only refreshes its own view.
• Bulk drains have their own success action (submitEmptyQueuesRequestSuccess); the shared success effect listens to both the singular and bulk forms and routes to either deleteEmptyQueueRequest or startPollingEmptyQueueRequest depending on whether the drop request is finished.
• Connector-canvas actions for Empty Queue, Empty All Queues, List Queue, Drain, and Cancel Drain are wired through this slice.

Cleanup and hardening (second commit)

A follow-up commit addresses minor items grouped by theme:

• Correctness
  • EmptyQueueState clears the unused identifier on submit so subsequent polling/deletion can never run against a stale connectionId or processGroupId.
  • Replaced processGroupId! non-null assertions in pollEmptyQueueRequest$ and deleteEmptyQueueRequest$ with explicit guards that dispatch emptyQueueApiError if neither id is present.
  • Added hasAttemptedLoad to ConnectorControllerServicesState so the controller services skeleton is only shown on the very first load — retries after a failed initial load no longer re-flash the skeleton.
• Design
  • Tightened navigateToControllerServices to require processGroupId and dropped the unreachable route fallback in the effect.
• Cleanup
  • Pruned ten unused selectors from connector-controller-services.
  • Removed an unused navigateBackToConnectorCanvas action and effect.
• Tests
  • Added reducer and effect coverage for the new bulk-success action and for the cleared-identifier and null-id guard paths in EmptyQueueEffects.
  • Added a readonly-derivation spec for EditControllerService covering the explicit flag, missing write permission, and non-DISABLED run status.
  • Updated controller-services component and reducer tests for hasAttemptedLoad.

Follow-ups

The connector canvas's List Queue action navigates to the existing /queue/{connectionId} page. That page's queue listing relies on the standard nifi-api/flowfile-queues/{id}/... endpoints; full functionality for connections inside a connector's runtime depends on those endpoints resolving in the connector context and is tracked separately.

[rfellows]

Will review...

[rfellows]

Excellent, @mcgilman 👍