Doc with phase 0 & phase 1 reqs.

We would like to investigate replacing JupyterHub with the Kubeflow notebook controller to make it easier to address some other planned enhancements such as custom images, deploying NB servers in separate namespaces, authentication, support for other IDEs such as RStudio, and integration of other KF components. In addition, we believe it can help with other issues we've experienced related to failures starting notebook servers, notebook server tolerations, etc.

We want to ensure we don't lose these capabilities currently provided by JupyterHub:

• "Spawner" page for defining NB server options. This includes all items on the spawner page and ensuring settings are sticky (remembered) based on the previous session.
• ability to stop server
• admin visibility into NB server sessions within cluster. This is the JupyterHub admin view.
• ability for admins to stop NB server sessions for other users
• ability to quickly get to JupyterLab interface for notebook sessions - we don't want to introduce more friction in creating NB servers and getting in JupyterLab.
• quick starts, tutorials related to JupyterHub tasks. These would need to be modified, but we want to provide the same level of doc.
• for any NB server creation issues, provide user-friendly error messages so users know how to correct issues and allow users to recover right away (i.e. avoid 10 minute delay before being able to try to start server again). RHODS-1585, RHODS-1493
• tolerations for Jupyter notebook sessions that need GPUs: RHODS-540

Doc with comparison between KFNBC & JH