Add `Remember me` to the SAML workflow

What does this MR do and why?

We added a Remember me checkbox before the Sign in button in the SAML authorization workflow.

Changes in the UI:

• replaced the group name by a link in the title
• removed emphasised group name in the explanatory paragraph

Screenshots or screen recordings

Before

After

How to set up and validate locally

It is kind of tricky to test locally the whole SAML workflow. Maybe the easier way it's, once login, go to this page: https://gdk.test:3443/groups/flightjs/-/saml/sso.

See also: https://gitlab.com/gitlab-org/manage/authentication-and-authorization/discussion/-/issues/32#note_1002860588

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.