Feature: OIDC - SSO: Ability to disable auto user creation

[rayzilt]

Please describe the problem you'd like to be solved
Configuration option to enable/disable auto user creation when using OIDC - SSO implementation.

Describe the solution you'd like to see implemented
Able to configure this by variable

---

For Artefactual use:

Before you close this issue, you must check off the following:

• All pull requests related to this issue are properly linked
• All pull requests related to this issue have been merged
• A testing plan for this issue has been implemented and passed (testing plan information should be included in the issue body or comments)
• Documentation regarding this issue has been written and merged
• Details about this issue have been added to the release notes

[rayzilt]

Looking at code of 1.18.x I think it's already implemented. When a user tries to login but does not have a account and no roles defined, it will be ignored.

My feature request came from 1.15.x

https://github.com/artefactual/archivematica/blob/stable/1.18.x/src/archivematica/dashboard/components/accounts/backends.py#L157

[rayzilt]

Re-opening issue when talking to @mamedin. Like AtoM it's desired to have a means of control to enable/disable auto creation of users in Archivematica