Group-SAML adds users to group upon linking identity

What

Users should be given Guest access to the group when they sign in to Group level SAML as part of &40 (closed)

Why

I've split this from https://gitlab.com/gitlab-org/gitlab-ee/issues/4514 for discussion and in case I want to get that into review earlier, but might impement it in the same MR

Related

• &40 (closed)
• https://gitlab.com/gitlab-org/gitlab-ee/issues/4513
• https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4076