Make controller UI better

[Venjy]

Good News!

We will have an UI in this repo 🎉
You can see some screenshots in this PR.

Current Status

To be honest, the UI currently only has the most basic functions:

• Create, view, delete namespace
• Create, view, delete cluster
• View nodes

Furture Planing

• Support Migrate

What We Need

To make the UI better, we are asking for your opinion, including but not limited to the following:

• What do you think a useful Migrate page should look like?
• For the existing UI, what can be optimized and improved?
• What other functions do you think the UI should include?
• Have you seen similar great tools? Where can we learn from them?

Welcome to leave any suggestion about UI in this discussion.