Make it possible to configure the Nuxeo Drive root bindings from the Nuxeo server UI

nuxeo-drive-server bundle should include a new action available for folders and workspaces to register them as root bindings for synchronization.

A new operation should make that list of root bindings automatically available along with new Audit service Event so that nxdrive client can list and be notified of new bindings to register (or unregister).