Run a hosted demo of the GitProxy dashboard ☁️

It would be fab for newcomers (both contributors and users) of GitProxy to quickly get to grasps with the purpose and impact of the project. Whilst not all users will take advantage or use the dashboard, it is certainly helpful to understand the concept of GitProxy and its endless capability as a self deployed interception point for git traffic.

```[tasklist]
### Tasks
- [ ] Build and run the latest version of `@finos/git-proxy` dashboard from our microsite
- [ ] Attach the demo to the `/demo` endpoint of the site
- [ ] Consider security implications of a deployed demo in the comments below
```