Provide nested view for all groups and projects list
## Problem
Most list views are currently a flat list of groups or projects, making it difficult to understand whether a group contains subgroups. This can lead to accidental deletion of content because a user might not understand that a group contains more content than displayed in that list. Some lists, such as Your Work > Groups, are nested, but only display groups and subgroups.
Ultimately, we would like to allow users to search content across combined groups and projects list.
### Current state
| List | Flat | Group-nested | Fully nested |
| ------ | ------ | ------ | ------ |
| Admin Area > Groups | :heavy_check_mark: | | |
| Admin Area > Projects | :heavy_check_mark: | | |
| Organization > Groups and projects > Projects | :heavy_check_mark: | | |
| Organization > Groups and projects > Groups | :heavy_check_mark: | | |
| Explore > Groups | | :heavy_check_mark: | |
| Explore Projects | :heavy_check_mark: | | |
| Your Work > Groups | | :heavy_check_mark: | |
| Your Work > Projects | :heavy_check_mark: | | |
| User Profile > Groups | :heavy_check_mark: | | |
| User Profile > Projects | :heavy_check_mark: | | |
| Group overview | :heavy_check_mark: (Shared groups and Shared projects tab) | | :heavy_check_mark: (Subgroups and projects tab) |
## Proposal
We should consider providing a nested view as we do in the [group overview](https://gitlab.com/gitlab-org) page.
issue