external directory: reset auth source when disabled

this allows existing users to login (including the owner itself)

The alternative is to have some system where we have unique superadmin users across cloudrons which don’t get trampled upon by a sync. This is a bit unrealistic. For the future, we could also design this such that ldap auth is asked for in the initial step i.e at superadmin creation time.

If LDAP connection is lost/down, user can always use 'cloudron-support —owner-login'

src/externalldap.js

@@ -81,6 +81,8 @@ async function setConfig(newConfig) {
     if (error) throw error;
 
     await settings.setJson(settings.EXTERNAL_LDAP_KEY, newConfig);
+
+    if (newConfig.provider === 'noop') await users.resetSource(); // otherwise, the owner could be 'ldap' source and lock themselves out
 }
 
 // performs service bind if required