This makes `bootstrapModuleFactory` wait for promises
returned by `APP_INITIALIZER`s, also making `bootstrapModuleFactory` async.
I.e. now `bootstrapModule` and `bootstrapModuleFactory` behave in the
same way.
This ensures that all code from module instantiation, to creating
`ApplicationRef`s as well as calling `APP_INITIALIZERS` is run
in the Angular zone.
This also moves the invocation of the initializers from the `ApplicationRef`
constructor into the `bootstrapModuleFactory` call, allowing initializers
to get a hold of `ApplicationRef` (see #9101).
Fixes#9101Fixes#10363Fixes#10205