[ember-cli] Replace http-mocks feature from with Mirage

[mehulkar]

I recently discovered that ember-cli has the ability to setup server mocks using ember g http-mock posts. It installs the http-mock library and sets up a server/ folder with some boilerplate.

This feature is documented on the old ember-cli website: https://ember-cli.com/user-guide/#mocks, but not in the new guides as far as I can see: https://cli.emberjs.com/release/.

I personally use ember-cli-mirage in every project, and although it can feel bit larger in terms of surface area, I think the request handling bit of it can be given first class support in Ember CLI core. The database part (schema/db/factories/models) of Mirage is a more advanced feature (which I love), but could come from userland (similar to something like faker.js).

Considering that Mirage is moving to a framework-agnostic setup, I think this is a good time to revisit how Ember CLI can integrate it (probably by including it in package.json, rather than exposing it as an opaque generator command.)

[jrjohnson]

I've seen a couple questions on SO recently about server mocks (eg: https://stackoverflow.com/questions/57333908/ember-js-how-can-i-test-express-server-mock). I think this was a great feature a few years ago that probably needs to go away (or at least recommend users to go another way for almost everything it used to support).

[ming-codes]

I kinda hoped mirage would integrate with http-mock better as the client side fake generation is super slow. I have a relatively small app that takes 5 seconds to load because it's spending the time to generate all the fake objects. Since Ember doesn't have hot module reload, this happens on every code change.

I love the mirage workflow, but it's really unacceptable to take 5 seconds to see my change.

[mehulkar]

Opened #576 for this.