Notebox Access levels

[deyloop]

The separate noteboxes need to be able to see each other.

For example if I am in the private notebox, I need to be able to see
notes from public notebox when performing searches.

This should be controlled by access levels.

A notebox will have search visibility of noteboxes that have a lower
access level than it.

Commands required:

• Check access level of current notebox

  nb repo.access_level

• Set the access level of current notebox

  nb repo.access_level 3

And of course, the search functionality will be affected accordingly