Group-level DevOps Adoption
## Overview
The [DevOps adoption table](https://docs.gitlab.com/ee/user/admin_area/analytics/dev_ops_report.html#devops-adoption) is a valuable feature for leadership to see which GitLab stages and features have been adopted by their teams. The feature was implemented in a way that creates two limitations we would like to resolve.
1. This is an instance-level feature which means it is only available to self-managed customers.
1. The feature is accessed through the Admin Area, which further restricts access to administrators. This feature is more likely to be valuable to executives and decision makers who are not administrators of the GitLab instance.
## Proposal
Add the Adoption Report to Groups:
- [x] [Group-level API.](https://gitlab.com/gitlab-org/gitlab/-/issues/321087) ~backend
- [x] [Add "DevOps Adoption" to the group-level left-nav.](https://gitlab.com/gitlab-org/gitlab/-/issues/321080) ~frontend
- [x] [Add group-level "DevOps Adoption" page, which only displays data and sub-groups that exist within the given group.](https://gitlab.com/gitlab-org/gitlab/-/issues/321082) ~frontend
- [x] [If the given group has no sub-groups, the modal should either be disabled or say "There are no sub-groups to select from."](https://gitlab.com/gitlab-org/gitlab/-/issues/321083) ~frontend
### Considerations
- Use "lazy enabling" to minimize performance issues associated with processing data for every group in a very large instance such as gitlab.com. Lazy enabling means groups are disabled by default but if a user visits the Adoption Report page for a group, all of the sub groups are automatically enabled and can be added to the table.
- Keep the feature in the Ultimate tier for now while we monitor adoption and performance
- Require Reporter or higher group access to view the feature
- Users can add any descendants of the group to the table
### Pros
- The DevOps Adoption feature becomes available to our SaaS customers and they can get an organization-wide view of DevOps adoption by viewing the feature from their top-level group (the group that is linked to their license)
- The DevOps Adoption feature becomes available to non-Admin users for both self-managed and SaaS
### Cons
- Self-managed users will still need to access the feature through the Admin Area if they want an instance-wide view of adoption (unless they have organized all of the groups in their instance to descend from a top-level group)
## References
See also https://gitlab.com/gitlab-org/gitlab/-/issues/235817 for a similar discussion about DevOps Score
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