internal: improve @warp-drive/diagnostic DOM Reporter

[runspired]

While @warp-drive/diagnostic has been able to be dropped in for qunit in three packages now, its DOM reporter is not as feature rich as qunit's.

• [x] add comprehensive readme
• [ ] add to EmberData contributing guide
• [ ] add code-doc comments for all public exports and methods
• [ ] display individual results
• [ ] make hide/show passed work
• [ ] make hide/shoe individual work
• [ ] make url params work
• [ ] render container CSS (make it good and also fast)
• [ ] lightmode css?

Feature Parity work

• [ ] make test-rerun work
• [ ] rerun failed tests first

New Feature work

• [x] concurrent mode
• [ ] parallel mode
• [ ] randomized mode
• [ ] memory stats