Updates for all angular.io links to the new angular.dev domain. Additionally, adjustment to new resources where the equivalent does not exist on the new site (e.g. Tour of Heroes tutorial)
Use promise based methods to reduce RXJS usage and boiler-platting.
BREAKING CHANGE: Several changes to the `SchemaRegistry`.
- `compile` method now returns a `Promise`.
- Deprecated `flatten` has been removed without replacement.
1. update the return type of 'validateOptionsWithSchema' to make it
conform the signature of engineHost.registerOptionsTransform
2. fix minor naming issue