this fix the nextcloud login + drive selector (chroot)
fix also invitation / magic link
also correct the UX: once user has logged in nextcloud, show an explicita page
Bring chroot to nextcloud capability: login on Nextcloud via username="{user}~{folder-uuid}
Doing a such login will chroot the folder folder-uuid
If user has several folder as root (parent=None), the login flow will request which
folder user want to chroot