notebooks: persistence ui
Created by: novoselrok
This PR migrates the existing search notebooks interface to use the persistence API. It includes a listing page with two tabs ('My Notebooks' and 'Explore notebooks') and a single page with editable title, visibility options, settings, and editable notebook content.
For reviewers: Despite many attempts, I could not find a good way to split up this PR. Instead I tried to chunk the changes into small sensible commits. Therefore I suggest you review commit by commit instead of the whole PR at once.