Ability to see subtasks on the on the backlog in Team-Managed Projects

Issue Summary

Currently, subtasks don't show in the backlog of Team-Managed Projects. Users need to click into the parent issue to see the subtasks.

Steps to Reproduce

Go to the backlog of a Team-Managed Project, you'll see that you can't see subtasks/child issues in it unless you explicitly open the parent. You also can't search subtasks. 

Expected Results

1. Go to a Team-Managed Project (you can see the project type in the bottom left hand corner)
2. Go to the backlog
3. Expected: You can see the subtasks/child issues

Actual Results

The backlog doesn't show subtasks/child issues. ...

Workaround

Currently, no workaround unless you use a Company-Managed project.