[ENH] - Integrate jhub-app in Nebari

[pavithraes]

Feature description

Amit worked on a CDS Dashboards replacement here: https://github.com/nebari-dev/jhub-apps

We need to integrate this is Nebari.

Value and/or benefit

Adds back some features we deprecated with CDS Dashboards.

Anything else?

No response

[pavithraes]

This will be added in the next release, but can be disabled. When disabled, the current JupyterHub interface will be the same. Enabling/disabling jhub-apps will require redeployment.

Note that we need to add "stop server" functionality to jhub-apps before/during merge into Nebari.