Provide an audit report of user permissions by group and project
### Problem to solve
Compliance-minded customers require a list of permissions for each user across all groups and projects on their instance.
Currently, a summary of this information isn't readily available.
### Proposal
Provide a view or export that displays the projects and groups that each user has access to.
### Epic implementation order
1. [MVC: Create a custom API endpoint for listing all group and project permissions for users](https://gitlab.com/gitlab-org/gitlab/-/issues/215658)
2. [Show total group and project count for users in admin users table](https://gitlab.com/gitlab-org/gitlab/-/issues/215149)
3. [Make available a list of User Permissions per Group and Project](https://gitlab.com/gitlab-org/gitlab/-/issues/1772)
epic