Implement Manage Multiple Profiles Upstream

[wg102]

This use to be a feature missing in the UI. It was fixed in #7

Some talk with upstream might be needed since the feature was not discussed yet.

The commits related to this feature that need to be integrated into upstream code are:
(to be added)

[wg102]

This might be covered by something @davidspek is working on. Adding fine grained permissions management for namespace sharing and it would include managing contributors for each namespace.

[davidspek]

It doesn't do much more than list and delete rolebindings at this point, but I think this shows the general idea. The current setup will also allow for multiple admins for each namespace (due to the profile-controller the original admin cannot be removed as admin by other admins, which is a good thing in most scenarios).

I'm planning to borrow some design ideas from https://github.com/sighupio/permission-manager, particularly for creating/viewing (Cluster)Roles.

I'm also thinking of extending this UI so the Kubeflow cluster admin can manage Kubeflow profiles, although this will require some special permissions and modification to the profile controller.