Add contribution-analytics-graphql feature flag

What does this MR do and why?

Adding a new feature flag to help roll out #376001 (closed), the conversion of Contribution analytics to GraphQL

This is being created to replace !108273 (merged), which needed to be reverted due to lack of GraphQL pagination.

Changes:

• Adds contribution_analytics_graphql feature flag
• Migrates legacy components to the legacy_components folder
• Create a new App skeleton that fetches the data via GraphQL
• Renders App or LegacyApp based on the feature status for the Group

Next steps:

• Add the child components for the new App
• Add GraphQL pagination

Screenshots

Feature On	Feature Off

How to set up and validate locally

1. Visit any group contribution analytics page such as http://gdk.test:3000/groups/flightjs/-/contribution_analytics
2. Validate the charts/table are rendering without error
3. Feature.enable(:contribution_analytics_graphql, Group.find(GROUP_ID))
4. The page should not render any content, but there will be a GraphQL request sent on page load

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.