feat(ElementInjector): implement ElementInjector

Initial implementation of ElementInjector.

Works:
1. The creation of proto element injector trees
2. Bindings
3. The instantiation of element injectors
4. The instantiation of directives
5. Visibility: Parent and Ancestor
6. Delegation to application injectors
7. Error handling

Missing features:
1. Handling components.
2. Setting "special" properties (e.g., Element, View).
3. Cycle detection
4. Distance
5. Text nodes
Don't do this here since you will cause reading of all of the keys. Most of the time we will only have 1 or 2 and so reading them all is unnecessary.