FEAT : Add Model Dashboard

[Bojun-Feng]

Replace the default Gradio page with a React.js framework for a multi-page dashboard. Right now there is only one page named "Running Models", which displays all running models, launches Gradio WebUIs for them, and terminates them. The file structure is set up such that it should be easy to add more pages in the future.

Created as a first step in resolving #93.
Resolves #221.
Resolves #311.

Here is the file structure overview:

• Added folder /inference/xinference/web/ui/, where all frontend code is hosted
• Each shared or public component used by multiple pages is stored ui/src/components folder
• Each page has its own subdirectory in the ui/src/scenes folder
• The ui/src/App.js file is used to route the pages and link them together

To-do list:

• edit or remove README.md in /inference/xinference/web/ui/
• test ChatGLM compactibility