Step 1 MR Refactor (FE): Add info/error messages to security widget summary
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## Why are we doing this work
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Currently for a MR, after the pipeline for the MR completes, a security report summary is shown on the MR page:
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We want to add descriptive information/error messages to give the user better info on what's going on with the security summary and steps they can take to fix any issues with it.
## Relevant links
Mocks B5 - B6
* [B5. Use cases: Non-error states](https://gitlab.com/gitlab-org/gitlab/-/issues/12896/designs/b5-use_cases_non-error-states.png)
* [B6. Use cases: Error States](https://gitlab.com/gitlab-org/gitlab/-/issues/12896/designs/b6-use-cases_error-states.png)
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## Non-functional requirements
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- [ ] **Documentation:** will need to be updated to cover the new messages that can be displayed
## Decisions
- [Hold off on implementing the `resolved` alert for now](#note_565144642). This has been extracted to https://gitlab.com/gitlab-org/gitlab/-/issues/329910.
- [De-nest the message display logic](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/20954#note_564335898) for showing the base report is out of date / the source branch is behind the target branch.
- Implement the failed jobs alert as-is, using a [GraphQL query to determine if any failed](https://gitlab.com/gitlab-org/gitlab/-/issues/275818#failed-jobs-query).
- [Keep using the existing `base_report_out_of_date`](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/20954#note_564335898) returned from the scanner comparison endpoints, rather than switching to the new `MergeRequest.securityReportsUpToDateOnTargetBranch` GraphQL field.
- [Expose `securityReportsUpToDateOnTargetBranch` to the MR widget in order to display the widget in the case that scanners were enabled _after_ the source branch was created](#note_562802638).
- [Keep using the existing `enabled_reports` field rather than the new `MergeRequest.hasSecurityReports` GraphQL field](#note_562802638).
- [Keep using the existing `diverged_commits_count` field rather than the new `MergeRequest.divergedFromTargetBranch` GraphQL field](#note_562802638).
- Improving/implementating loading states is tracked in https://gitlab.com/gitlab-org/gitlab/-/issues/287706.
- [Improving the l18n/l10n strings](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/46167#note_445227230) will be handled in https://gitlab.com/gitlab-org/gitlab/-/issues/287706, since they are related to the loading state(s).
## Implementation plan (likely out of date, see https://gitlab.com/gitlab-org/gitlab/-/issues/267504#note_607944913)
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Note that some of the unchecked items below have been drafted in a PoC MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64608.
~frontend
- One or more security jobs failed (see PoC MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64608)
- **The design/appearance of this alert is currently under discussion, and may still change. See [this thread](#note_596260647))**.
- Design 
- [ ] Expose/consume `failures_project_pipeline_path` for link to job failures
- [ ] Add apollo query for [getting security jobs' statuses](https://gitlab.com/gitlab-org/gitlab/-/issues/275818#failed-jobs-query). If any job has `detailedStatus.text === 'failed'`, show the alert.
- [ ] Probably need to add a new slot to `ReportSection` component between the `.media` element and before the `body` slot containing element to contain the alert
- User's source branch is behind the target branch
- [x] [De-nest the message display logic](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/20954#note_564335898) for showing the base report is out of date / the source branch is behind the target branch. (see https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64090)
- User enabled security scanners after source branch was created (see PoC MR https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64608)
- [ ] Expose [`security_reports_up_to_date?`](https://gitlab.com/gitlab-org/gitlab/blob/b9fe40b05fae29b7280374665647bd94b8052858/ee/app/models/ee/merge_request.rb#L273) method on `MergeRequestPollWidgetEntity`
- [ ] Render security widget if there are any `enabled_reports` _or_ if `security_reports_up_to_date?` is `false`.
- [ ] Ensure widget displays message `Security scanning detected no results for the source branch only` and shows the `error` status rather than `success` status. Might require some Vuex work.
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