Preserve user and its data from deletion when user_external app disabled

[nshah14285]

Is your feature request related to a problem? Please describe.
We would like to use "user_external" app for external authentication but at the same time we also want to preserve user data when we disable or remove the "user_external" app settings from config.php file or settings get lost from config.php file due to some reason or on Nextcloud upgradation.

Describe the solution you'd like
On user authentication, store user values in Nextcloud core table as well. I think this way users and it's data will be preserve.

[prismopensource]

We would like the same, since the developer doesn't have time to develop this app anymore it will probably be obsolete soon so I'd like to have a way to migrate these user_external users to normal Nextcloud users as easily as possible.