Allow manual bypass of auto_sign_in_with_provider

What does this MR do?

This MR gives users who configured SSO using auto_sign_in_with_provider to access the login form manually in order to login technical users (admin), or external users.

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

I added a small change in the way redirection URIs are compared to the login path in order to avoid a redirection loop. Without this fix, accessing users/sign_in?noautosignin would cause a redirection loop. The check now ignores query parameters to avoid that.

Why was this MR needed?

In my organization, we have 99% of users using a Single Sign On system (CAS) and only a couple of external users and technical accounts. In that situation, it is disappointing for our users to have to click on the SSO link on the authentication page and we would love to enable auto sign-on, but we cannot use auto_sign_in_with_provider because the external and technical accounts would not be able to login anymore.

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?

#3786 (closed)