Add basic ember-cli addon structure

[Turbo87]

This PR adds the base structure for ember-cli to recognize this project as an addon and continues the work started in #12412.

This PR only adds the base structure, more advanced things should IMHO be done in unrelated PRs and can be done in parallel once this one is merged:

• import blueprints from ember-cli (see Import blueprints from ember-cli #13029)
• import shims from ember-cli-shims (see provide ember-core from NPM #13022)
• add necessary Ember.js files to the broccoli trees (see provide ember-core from NPM #13022)

/cc @mmun @stefanpenner

[mmun]

Looks good.

@rwjblue: is there a basic sanity test we could add?

[Turbo87]

@mmun I don't think there is anything we can test at this point, but once we start testing the blueprints this should be included in the tests.

see Turbo87/ember.js@6c48a46...0edf21c

[stefanpenner]

@Turbo87 would you like me to rebase #12412 and submit it as a PR this this branch? (I am flying today, but can likely doit once i arrive home)

[stefanpenner]

Oh, its worth noting on of the remaining pieces that prevented #12412 from landing was also extracting the tests, now that @trabus has extracted us some lovely test helpers, we should be in a much better place.

[Turbo87]

@stefanpenner @mmun and I discussed this on Slack and came to the conclusion that it would be easiest to start fresh and pull the useful bits from #12412 over one-by-one. As mentioned above I think it would be a good idea to first make this project an addon (this PR) and then use separate PRs for the tasks listed above (blueprints, shims, ...).

[stefanpenner]

@Turbo87 ya likely, as the blueprints and stuff are not out of sync.

If you need me to doit, let me know. Now that we are further along with other extractions (that i discovered were required while working on that PR), it should be relatively not horrible to redo.

[Turbo87]

@stefanpenner as the blueprint stuff seems relatively straight forward I'd appreciate it if you could tackle the "add necessary Ember.js files to the broccoli trees" point. this seems to have been worked on in #12412 but I'm not sure if was finished (and how it actually works).

[stefanpenner]

Ya I can add that

[Turbo87]

@stefanpenner cool, thanks!

how do we proceed in getting this PR merged in the meantime? can you r+ or do we need more reviews/opinions first?

[Turbo87]

🎉 Gracias!