message: [TaskManager] Update task-selection demo to use subscribeToTask()
  ## Description
  This PR updates the task-selection demo to use `subscribeToTask()` instead of `volunteerForTask()`.
  ## Other information or known dependencies
  [AB#1470](https://dev.azure.com/fluidframework/235294da-091d-4c29-84fc-cdfc3d90890b/_workitems/edit/1470)
diff: @@ -49,7 +49,7 @@ export class TaskManagerDiceRoller extends DataObject implements IDiceRoller {
  const taskManagerHandle = this.root.get<IFluidHandle<TaskManager>>(taskManagerKey);
  this._taskManager = await taskManagerHandle?.get();
  - this.volunteerForAutoRoll();
  + this.subscribeToAutoRoll();
  }
  private get taskManager() {
  @@ -68,27 +68,25 @@ export class TaskManagerDiceRoller extends DataObject implements IDiceRoller {
  this.root.set(diceValueKey, rollValue);
  };
  - public volunteerForAutoRoll() {
  - // Try to take the task and wait until we get it. This may wait forever if the current task holder
  - // doesn't release it.
  - this.taskManager.volunteerForTask(autoRollTaskId)
  - .then(async () => {
  - // Attempt to reacquire the task if we lose it
  - this.taskManager.once("lost", () => {
  + public subscribeToAutoRoll() {
  + // Subscribe to the auto roll task. This will constantly keep us in queue for the task until we get it. If we
  + // lose the task assignment we will automatically re-enter queue.
  +
  + this.taskManager.on("lost", (taskId: string) => {
  + if (taskId === autoRollTaskId) {
  this.emit("taskOwnershipChanged");
  this.endAutoRollTask();
  - this.volunteerForAutoRoll();
  + }
  });
  +
  + this.taskManager.on("assigned", (taskId: string) => {
  + if (taskId === autoRollTaskId) {
  this.emit("taskOwnershipChanged");
  this.startAutoRollTask();
  - }).catch(() => {
  - // We're not going to abandon our attempt, so if the promise rejects it probably means we got
  - // disconnected. So we'll try again once we reconnect. If it was for some other reason, we'll
  - // give up.
  - if (!this.runtime.connected) {
  - this.runtime.once("connected", () => { this.volunteerForAutoRoll(); });
  }
  });
  +
  + this.taskManager.subscribeToTask(autoRollTaskId);
  }
  private startAutoRollTask() {
  