Upgrade/Rewrite EmberJS example for Ember Octane

[sukima]

EmberJS has introduced a significant change to its paradigm. This latest edition is called Octane and has been in use in the wild for about a year now. The future of EmberJS will be to continue expanding on this newer paradigm.

The TODO app—being a representative of modern EmberJS programming—should reflect this as well. It means upgrading the current example to the latest version of Ember and converting the current code to use Octane patterns.

This issue is a request to update and modernize the current EmberJS example.

[NullVoxPopuli]

I have a version of it implemented here: https://github.com/NullVoxPopuli/ember-todomvc-tutorial/tree/master/steps/00-finished-todomvc/todomvc

This is what is featured in the EmberJS MDN tutorial

[NullVoxPopuli]

I also started a PR here: #2103 but either C.I. is broken or a rebase will get it passing again

[sukima]

I was just going to do it because I thought it was something fun to do on a holiday. But the contributing guides said I had to make an issue first and get permission discuss it first. 🤷

[NullVoxPopuli]

Ah, maybe that's why my PR has no comments. Hmm. Feel free to pick it up if you want. I'll add you to the fork

[NullVoxPopuli]

Gonna do this here #2209 but as Polaris, instead of Octane