Design exploration for cycle analytics: instance/group-level analytics and charting

Description

Cycle analytics is a feature with a lot of potential. Currently, this cool feature is only available at the project level and is a bit challenging to find - it's the 3rd option available on a mouseover of "Project" in the sidebar.

Making cycle analytics only available on a project-by-project basis makes it very hard to use. Organizations with many projects can't use this information: it's too granular, hard to click into every project to view, and makes "not enough data" issues more likely.

We'd also like to consider the problems framed in https://gitlab.com/gitlab-org/gitlab-ce/issues/45304 in this issue as well.

Problems

• How can we make Cycle Analytics useful for organizations with many projects?
• How can we increase the visibility of Cycle Analytics, so that more people are aware of this feature?
• How can we visualize cycle analytics trends over time?

Proposal

We should consider a new design for Cycle Analytics that covers a group and for an instance:

• A user should be able to interact with a unified Cycle Analytics page. I should be able to specify the scope of what I'm looking at, and narrow the information presented from instance > group > project.

• Relocate Cycle Analytics to a more prominent location in the UI: the analytics icon in the navbar here in https://gitlab.com/gitlab-org/gitlab-ce/issues/41416. Make instance-level cycle analytics the default page.

• Allow metrics to be visualized (charted) over time. Proposed by James:

  • 7 days, chart should show the twelve most recent 7 day periods (chart spans ~3 months)
  • 30 days, chart should show the twelve most recent 30 day periods (chart spans ~1 year)
  • 90 days, chart should show the twelve most recent 90 day periods (chart spans ~3 years)