feat(core): properly support inheritance

## Inheritance Semantics:

Decorators:
1) list the decorators of the class and its parents in the ancestor first order
2) only use the last decorator of each kind (e.g. @Component / ...)

Constructor parameters:
If a class inherits from a parent class and does not declare
a constructor, it inherits the parent class constructor,
and with it the parameter metadata of that parent class.

Lifecycle hooks:
Follow the normal class inheritance model,
i.e. lifecycle hooks of parent classes will be called
even if the method is not overwritten in the child class.

## Example

E.g. the following is a valid use of inheritance and it will
also inherit all metadata:

```
@Directive({selector: 'someDir'})
class ParentDirective {
  constructor(someDep: SomeDep) {}

  ngOnInit() {}
}

class ChildDirective extends ParentDirective {}
```

Closes #11606
Closes #12892

modules/@angular/core/test/util/decorators_spec.ts

@@ -53,7 +53,7 @@ export function main() {
     it('should invoke as decorator', () => {
       function Type() {}
       TestDecorator({marker: 'WORKS'})(Type);
-      const annotations = Reflect.getMetadata('annotations', Type);
+      const annotations = Reflect.getOwnMetadata('annotations', Type);
       expect(annotations[0].marker).toEqual('WORKS');
     });