Add scanners tab to security configuration page

What does this MR do and why?

Add scanners tab to security configuration page

Show scanners tab on group security configuration page
when group_security_configuration_scanners_tab feature flag is enabled
List group's available scanners and show scan profile coverage bar

References

• issue: [Frontend] Add scanner list view to Group => Se... (#596597)
• epic: Release 0 (Crawl) - [SPM] Centralized Security ... (gitlab-org#21626)
• design: group_security_configuration_-_scanning_enabled.png

Screenshots or screen recordings

Before (or with feature flag disabled)	After
one tab: Security attributes (default)	two tabs: Scanners (default) and Security attributes
	loading state
	empty state

How to set up and validate locally

0. git checkout 596597-group-security-configuration-scanners-list-view
1. have a GitLab Ultimate license
2. enable https://gdk.test:3443/rails/features/group_security_configuration_scanners_tab
3. go to a group where you have at least the developer role (which grants the read_security_scan_profiles permission)
4. in the sidebar, choose Secure => Security configuration
5. verify that there's a new Scanners tab with a list of scanners and statistics about how many projects in the group have them enabled
6. (optional) go to a project => Secure => Security configuration => Profile-based scanner configuration and verify that Scanner column looks the same as it did before (this has been component-ized as scan_type_cell.vue)

MR acceptance checklist

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Related to #596597