Feature-request: sub-grouping environments

Summary

Environments group only on the first / in the name. This is annoying in our case, where we have many environments which can be grouped in 3 dimensions: Application, Environment, and Customer.

The cross-product of any two of the three dimensions is way larger than is reasonable to click through in the environments page (20+ applications, 20+ customers, 3+ environments (dynamically added/removed via CI)), so sub-grouping (e.g. application/customer/environment -> application/customer/environment) would help a lot in our case.

Steps to reproduce

Create the following environments

• a
• b/c
• b/d/e
• b/d/f/g

and look in the environments tab, this will show a and a folder b with in it c, d/e and d/f/g

Example Project

https://gitlab.com/matthias.vandemeent/subgrouping-environments

What is the current bug behavior?

Subfolders are not displayed as such

What is the expected correct behavior?

Subfolders are parsed & recursively displayed

Relevant logs and/or screenshots

Related:
gitlab-org/gitlab-ce#22539 (issue for environment grouping)
gitlab-org/gitlab-ce!7015 (merge request implementing environment grouping)