Create DAP Impact dashboard and expose in all scopes

What does this MR do and why?

Summary

This change consolidates the analytics dashboards experience for both group and project pages behind a new feature flag called consolidate_analytics_dashboards. When enabled, both group and project analytics pages will use a unified "explore" dashboard app instead of their separate legacy apps.

As part of this, the group and project filter components are improved to automatically detect the current page's group or project context (from the page's metadata) and pre-select it as the default filter — so users don't have to manually select their group or project when landing on the page. URL query parameters still take priority over this automatic detection.

The "GitLab Duo and SDLC trends" dashboard has been renamed to "DAP Overview" with layout and content updates, and a new empty "DAP Impact" dashboard has been added as a placeholder for future AI spend and impact reporting.

References

This MR builds off of this spike: !251957 (closed)

gitlab-org/gitlab#623385 gitlab-org/gitlab#623417

Screenshots or screen recordings

How to set up and validate locally

• Enable the consolidate_analytics_dashboards feature flag
• Navigate to Explore > Analytics dashboards
• You should see separate DAP Overview and DAP Impact dashboards
• Opening either dashboard will have no group/project selected by default
• Navigate to Analyze > Analytics dashboards for any group
• The same dashboards should appear in the list
• Opening either dashboard should default the scope to the current group
• Navigate to Analyze > Analytics dashboards for any project
• The same dashboards should appear in the list
• Opening either dashboard should default the scope to the current group & project

MR acceptance checklist

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Related to #623385