Use in-memory component to implement the Actuator API

[seeflood]

What would you like to be added:
Currently our Actuator quickstart demo use the apollo component,which connects to the apollo server by default.

However, due to the GFW, the github workflow can not connect to the apollo server when running the tests:

see #456

To solve this issue, we can:

• Use some in-memory component to implement the Actuator API.
  We can choose any one of the in-memory components, such as the state component, such as the pubsub component, etc.

• modify the quickstart and use the configs/config_in_memory.json instead, so that the demo won't try to connect to the remote server.

Why is this needed:
To solve the issue above, and make the quickstart more stable and testable

[akkw]

我想做这个，我们怎么沟通

[seeflood]

@akkw 啊不好意思，这个功能我已经做好合并进去了，因为还在写文档 所以这个issue 没关……
可以看下其他感兴趣的事情哈，见 #108 和 #470