Add django script to manage users in group

[Tompage1994]

What is this PR doing:

Allows you to add or remove users from groups for local users. This is needed when Keycloak auth is enabled as there is no way to manage local users otherwise and local users are required to be able to do CI type jobs. This script allows a workaround to be put in place and can be used in conjunction with the other Django scripts in this directory.

Reviewers must know:

No issue exists for this PR.

$ django-admin manage-user-groups ansible automation newgroup
Assigned group 'newgroup' to user 'ansible'
Assigned group 'newgroup' to user 'automation'

$ django-admin manage-user-groups --remove ansible automation newgroup
Removed group 'newgroup' from user 'ansible'
Removed group 'newgroup' from user 'automation'

Notes:

PR Author: Add a QE reviewer (exceptions); Reviewers: look for sound code, no code smells, docs & test coverage Merger: When merging, include the Jira issue link in the squashed commit

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[app-sre-bot]

Can one of the admins verify this patch?

[alikins]

@awcrosby Would this be useful for https://issues.redhat.com/browse/AAH-1955 ?

[awcrosby]

@Tompage1994 overall this looks good, are you able to GPG sign your commit?

[Tompage1994]

@Tompage1994 overall this looks good, are you able to GPG sign your commit?

Done