refactor(Type): merge Type and ConcreType<?> into Type<?> (#10616)

Closes #9729

BREAKING CHANGE:

`Type` is now `Type<T>` which means that in most cases you have to
use `Type<any>` in place of `Type`.

We don't expect that any user applications use the `Type` type.

modules/@angular/examples/core/ts/metadata/metadata.ts

@@ -8,7 +8,7 @@
 
 import {Attribute, Component, Directive, Pipe} from '@angular/core';
 
-var CustomDirective: Function;
+class CustomDirective {};
 
 // #docregion component
 @Component({selector: 'greet', template: 'Hello {{name}}!', directives: [CustomDirective]})