Currently, the only way to specify new providers for a `Route` and the
children is to create a new `NgModule` with those providers and use the
`loadChildren` feature. This is pretty confusing and a wholly indirect
way of accomplishing this task. With this commit, developers will be
able to specify a list of providers directly on the `Route` itself.
These providers will apply the that route and its children.
This feature was inspired by the upcoming standalone components feature.
This ties in there because, as mentioned before, the prior art for lazy
loading configs was to load an `NgModule`. This loaded module contained
new route configs _and_ could specify new providers. Separating those
two concepts, there should be a way to load _just_ some new routes, but
there should also be a way to specify new providers as well (something
you could do in the `NgModule` world and now will be able to do in the
world without any `NgModule` through this feature).
PR Close#45673