feat(capability): make capability depend on user, disable non-standard user backends, expose infos
The capability should not always return 'enabled' => true
. Sometimes we don't want to delete the user through Nextcloud (LDAP, SAML), sometimes the user is the last admin or even last user.
In those cases, we return false and add a text reason.
The deletion endpoint and the settings page have the same checks.
Finally, the eventual delay before deletion is also exposed as a capability
Edited by Thomas