alphatrion cli support

[kerthcet]

What would you like to be added:

I want to add a cli to alphatrion so that it can launch the dashboard with command like alphatrion dashboard.

Why is this needed:

A quick start for user to launch the dashboard.

Completion requirements:

This feature requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[kerthcet]

/milestone v0.1.0

[kerthcet]

/assign

Let me add the framework first.