Added authentiq provider to tests and updated documentation, gem and config file.

What does this MR do?

This MR polishes Authentiq integration and adds Authentiq to two unit tests about Omniauth.

Are there points in the code the reviewer needs to double check?

Whether there are any problems with enabling these tests.

Why was this MR needed?

To verify that the Authentiq integration works as expected with tests and keep the gem and documentation up to date.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

None