feat(ngcc): support marking an in-progress task as unprocessed (#36626)

This commit adds support for stopping processing an in-progress task
and moving it back to the list of pending tasks.

In a subsequent commit, this will be used to allow ngcc to recover when
a worker process crashes in the middle of processing a task.

PR Close #36626

packages/compiler-cli/ngcc/src/execution/tasks/api.ts

@@ -117,6 +117,16 @@ export interface TaskQueue {
    */
   markAsFailed(task: Task): void;
 
+  /**
+   * Mark a task as not processed (i.e. add an in-progress task back to the queue).
+   *
+   * This removes the task from the internal list of in-progress tasks and adds it back to the list
+   * of pending tasks.
+   *
+   * @param task The task to mark as not processed.
+   */
+  markAsUnprocessed(task: Task): void;
+
   /**
    * Return a string representation of the task queue (for debugging purposes).
    *

packages/compiler-cli/ngcc/src/execution/tasks/queues/base_task_queue.ts

@@ -63,6 +63,16 @@ export abstract class BaseTaskQueue implements TaskQueue {
     this.inProgressTasks.delete(task);
   }
 
+  markAsUnprocessed(task: Task): void {
+    if (!this.inProgressTasks.has(task)) {
+      throw new Error(
+          `Trying to mark task that was not in progress as unprocessed: ${stringifyTask(task)}`);
+    }
+
+    this.inProgressTasks.delete(task);
+    this.tasks.unshift(task);
+  }
+
   toString(): string {
     const inProgTasks = Array.from(this.inProgressTasks);