Add new analytics dashboards listing route and view

What does this MR do and why?

This MR begins the process of moving the product analytics dashboards across from /-/product_analytics/dashboards to /-/analytics/dashboards. There will be several MRs which progressively move parts over to make it easier to review:

MR/Issue	Purpose	Status
Add new analytics dashboards listing route and ... (!112321 - merged)	Create new route and view	👈 You are here
Create new analytics dashboards app (!112196 - merged)	Copy basic structure	In dev
Add product analytics specific dashboards to sh... (!112298 - merged)	Copy product analytics specific dashboards and visualizations	In dev
	Copy visualization designer and rename from panel designer	In dev
	Update menu item to point to the shared dashboards listing	In dev
Present call-to-actions to configure dashboards... (#388629 - closed)	Add new onboarding flow for product analytics dashboards in the list	Scheduled
Remove product analytics specific dashboard lis... (#390551 - closed)	Remove old product analytics dashboards code	Scheduled

This specific MR sets up the controller, route, and basic HAML view which will connect to the Vue app.

Screenshots or screen recordings

note: The next MR will add the Vue app and progress the view past the loading icon

How to set up and validate locally

1. Visit a projects analytics dashboard e.g. http://gdk.test:3000/gitlab-org/gitlab-test/-/analytics/dashboards
2. Validate that the page is rendered with a loading icon

To test the features data item, you will need to follow the instructions at https://gitlab.com/gitlab-org/gitlab/-/snippets/2474959 to enable Product Analytics on your GDK. Toggling these values will set the feature to true or false accordingly.

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.

Related to #388557 (closed)