blueprints/initializer-test: Add RFC232 variants

[snewcomer]

Progress on #15933

[rwjblue]

Thanks for working on this! I'm sorry for the run around, but I think we are narrowing in on a really nice future for these types of tests.

[rwjblue]

Similar to the conversation in the instance-initializer PR, lets tweak this to avoid the manual run loop usage and leverage only public APIs.

I believe the result here would be something like:

module('Unit | Initializer | other stuff', function(hooks) {
  hooks.beforeEach(function() {
    this.TestApplication = Application.extend();
    this.TestApplication.initializer({
      name: 'other stuff',
      initialize
    });

    this.application = this.TestApplication.create({ autoboot: false });
  });

  hooks.afterEach(function() {
    destroyApp(this.application);
  });

  // Replace this with your real tests.
  test('it works', async function(assert) {
    await this.application.boot();

    assert.equal(self.bar, true);
  });
});

See https://github.com/rwjblue/__emberjs-PR15945_demo/blob/master/tests/unit/initializers/other-stuff-test.js for a demo app...

[rwjblue]

Sorry for the run around on this. Thank you for working through it!