Resolve "CI view for SAST"

What does this MR do?

Frontend:

1. Moves security report code to shared folder.
2. Creates vue_shared folder under ee for security_reports
3. Creates a mixin with the common app methods (mr widget & pipelines tab)
4. Creates a utils file with all the common store methods
5. Moves the CSS into a different file
6. Renames all CSS classes from mr-widget to report-block
7. Adds support in the pipelines page to mount security reports app
8. Creates app to support more than one report, but only adds SAST now
9. Fixes typo in the name of a file
10. Adds check for not always render the collapse button
11. Add tests for the new tab
12. Create CE port - https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/17176
13. Adds Vue app to render the summary text in the pipeline widget
14. Updates the counter in the security tab

Screenshots (if relevant)

no vulnerabilities	with vulnerabilities

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #3776 (closed)