Fix ember-release + ember-beta build

[marcoow]

This adds testing for Ember 4 on CI. This is focused on making things work to unblock us but we should clean up afterwards. There's probably a number of things we can clean up etc. but we should first have coverage for Ember 4 on CI.

closes #2332

[marcoow]

@BobrImperator do you have any idea why the tests fail for the engine in test-app for Ember 4.0 but work for the classic-test-app with Ember 4.0?

I can't seem to spot the difference… I think that's the only thing keeping us from merging this and finally having Ember 4 covered properly on CI

[BobrImperator]

I believe the problem might be embroider macros acting up, this happens because of a condition inside ember-engines that conditionally registers a custom link-to for versions older than 3.24.1, for some reason in the test-app it's detecting older versions while in the classic it seems to be correct.

On the screenshot is the compiled file of classic-test-app while running against ember-4

[marcoow]

Awesome 🎉 I also added the Ember 4.0 scenario back in – can't hurt to test that as well