[ng-dev]: Consider `createComponent()`

[ersimont]

createComponent() is a new(-ish?) function. Evaluate whether to use it in ComponentContext, or stick with the existing wrapper approach.

[ersimont]

It may me important do package this together with #130. From angular/angular#62040:

Adds support for passing in Binding objects into TestBed.createComponent. This makes it easier to test components by avoiding the need to create a wrapper component. Furthermore, it keeps the behavior consistent between tests and the actual app.