Introduce explanation question mark icon tooltips MR widget for different tests

Problem

It's not clear enough to just state DAST or SAST and writing out the full name takes up to much space.

Proposal

Introduce explanation question mark icon tooltips MR widget for different tests

Design

• Provide a pop-over tooltip in which we can place an introductory summary and a link for further inspection if required by the user. For further reasoning see https://gitlab.com/gitlab-org/gitlab-ee/issues/4464#note_54786769

To be popped up from explanation question mark icons at:

• pipeline view security report image
• merge request widget security report image

Updated naming conventions and links

• SAST (Static Application Security Testing): https://docs.gitlab.com/ee/user/project/merge_requests/sast.html
• Dependency Scanning: https://docs.gitlab.com/ee/user/project/merge_requests/dependency_scanning.html
• Container Scanning: https://docs.gitlab.com/ee/user/project/merge_requests/container_scanning.html
• DAST (Dynamic Application Security Testing): https://docs.gitlab.com/ee/user/project/merge_requests/dast.html