devtools: Add cancel task operation to scheduled tasks

Renames useTriggerScheduledTask to useScheduledTasksOperations and adds
cancelTask alongside triggerTask, with shared isLoading/error state. Adds
CancelScheduledTask type to devtools-common and cancelScheduledTask to the
DevToolsApi interface and client, hitting the existing scheduler cancel
endpoint. The ScheduledTasksContent UI now shows both trigger and cancel
buttons per task row.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Made-with: Cursor

plugins/devtools-common/src/alpha.ts

@@ -18,6 +18,7 @@ export {
   devToolsTaskSchedulerCreatePermission,
 } from './permissions';
 export type {
+  CancelScheduledTask,
   ScheduledTasks,
   TaskApiTasksResponse,
   TriggerScheduledTask,

plugins/devtools-common/src/types.ts

@@ -133,3 +133,8 @@ export type ScheduledTasks = {
 export type TriggerScheduledTask = {
   error?: string;
 };
+
+/** @alpha */
+export type CancelScheduledTask = {
+  error?: string;
+};