Basic user management web ui

[C0rby]

I am opening this issue to document some ideas we have at ownCloud.

We would like to have a basic web UI to manage users. The web UI could talk to the idm using the graph API https://github.com/libregraph/idm/issues/9 These operations could be:

• list users
• add users
• delete users
• lock users

This web UI doesn't necessarily need to be included in this repository, I just wanted to document this somewhere.

A first idea was to port the UI from our accounts service. https://github.com/owncloud/ocis/tree/master/accounts/ui

This also opens some implicit requirements like we would like to send invitation mails when adding users.

cc: @micbar @butonic