Timer support

[kaibocai]

The SDK should support creating timer inside the orchestration

end-to-end example

  it("should be able to run an single timer", async () => {
    const delay = 3
    const singleTimer: TOrchestrator = async function* (ctx: OrchestrationContext, startVal: number): any {
      yield ctx.createTimer(delay)
    };

    taskHubWorker.addOrchestrator(singleTimer);
    await taskHubWorker.start();

    const id = await taskHubClient.scheduleNewOrchestration(singleTimer);
    const state = await taskHubClient.waitForOrchestrationCompletion(id, undefined, 30);

    const expectedCompletionSecond = state?.createdAt?.getTime()! + delay * 1000;
    const actualCompletionSecond = state?.lastUpdatedAt?.getTime();
    
    expect(state);
    expect(state?.name).toEqual(getName(singleTimer));
    expect(state?.instanceId).toEqual(id);
    expect(state?.failureDetails).toBeUndefined();
    expect(state?.runtimeStatus).toEqual(OrchestrationStatus.ORCHESTRATION_STATUS_COMPLETED);
    expect(state?.createdAt).toBeDefined();
    expect(state?.lastUpdatedAt).toBeDefined();
    expect(expectedCompletionSecond).toBeLessThanOrEqual(actualCompletionSecond!);
  }, 31000);

Tested on local, already support.

Reference: #4