feat(core): expose inputs, outputs and ngContentSelectors on ComponentFactory. (#15214)

E.g. for a component like this:
```
@Component({
  template: ‘<ng-content select=“child”></ng-content>’
})
class MyComp {
  @Input(‘aInputName’)
  aInputProp: string;

  @Output(‘aEventName’)
  aOuputProp: EventEmitter<any>;
}
```

the `ComponentFactory` will now contain the following:
- `inputs = {aInputProp: ‘aInputName’}`
- `outputs = {aOutputProp: ‘aOutputName’}`
- `ngContentSelectors = [‘child’]`

packages/compiler/src/metadata_resolver.ts

@@ -142,7 +142,26 @@ export class CompileMetadataResolver {
           ngfactoryFilePath(dirType.filePath), cpl.componentFactoryName(dirType));
     } else {
       const hostView = this.getHostComponentViewClass(dirType);
-      return createComponentFactory(selector, dirType, <any>hostView);
+      // Note: inputs / outputs / ngContentSelectors will be filled later once the template is
+      // loaded.
+      return createComponentFactory(selector, dirType, <any>hostView, {}, {}, []);
+    }
+  }
+
+  private initComponentFactory(
+      factory: StaticSymbol|ComponentFactory<any>, inputs: {[key: string]: string},
+      outputs: {[key: string]: string}, ngContentSelectors: string[]) {
+    if (!(factory instanceof StaticSymbol)) {
+      for (let propName in inputs) {
+        const templateName = inputs[propName];
+        factory.inputs.push({propName, templateName});
+      }
+      const outputsArr: {propName: string, templateName: string}[] = [];
+      for (let propName in outputs) {
+        const templateName = outputs[propName];
+        factory.outputs.push({propName, templateName});
+      }
+      factory.ngContentSelectors.push(...ngContentSelectors);
     }
   }
 
@@ -186,6 +205,11 @@ export class CompileMetadataResolver {
         componentFactory: metadata.componentFactory,
         template: templateMetadata
       });
+      if (templateMetadata) {
+        this.initComponentFactory(
+            metadata.componentFactory, metadata.inputs, metadata.outputs,
+            templateMetadata.ngContentSelectors);
+      }
       this._directiveCache.set(directiveType, normalizedDirMeta);
       this._summaryCache.set(directiveType, normalizedDirMeta.toSummary());
       return normalizedDirMeta;