Provide hint to create a personal access token for Git over HTTP

What does this MR do?

If internal auth is disabled and logged in user is not an LDAP user, present him with a reminder to create a personal access token to push or pull the project. Only show if user does not already have an active, non-impersonation personal access token. This is the web UI counterpart to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11986.

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

No.

Why was this MR needed?

Our GitLab instance is configured to use CAS authentication only; internal auth/sign-in is disabled. Our biggest support issue since we have gone into production is that users are trying to perform Git over HTTP authentication with their external credentials, rather than a personal access token. With this code change, users will have an indicator in the web UI to push them toward PAT creation.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

What are the relevant issue numbers?

Edited by username-removed-1113013