refactor(core): introduce NgModule.schemas

This allows Angular to error on unknown properties,
allowing applications that don’t use custom elements
to get better error reporting.

Part of #10043

BREAKING CHANGE:
- By default, Angular will error during parsing
  on unknown properties,
  even if they are on elements with a `-` in their name
  (aka custom elements). If you application is using
  custom elements, fill the new parameter `@NgModule.schemas`
  with the value `[CUSTOM_ELEMENTS_SCHEMA]`.

  E.g. for bootstrap:
  ```
  bootstrap(MyComponent, {schemas: [CUSTOM_ELEMENTS_SCHEMA]});
  ```

modules/@angular/compiler-cli/integrationtest/src/features.ts

@@ -7,7 +7,7 @@
  */
 
 import * as common from '@angular/common';
-import {Component, Inject, OpaqueToken} from '@angular/core';
+import {CUSTOM_ELEMENTS_SCHEMA, Component, Inject, NgModule, OpaqueToken} from '@angular/core';
 
 import {wrapInArray} from './funcs';
 
@@ -37,3 +37,16 @@ export class CompWithProviders {
 })
 export class CompWithReferences {
 }
+
+@Component({
+  selector: 'cmp-custom-els',
+  template: `
+    <some-custom-element [someUnknownProp]="true"></some-custom-element>
+  `,
+})
+export class CompUsingCustomElements {
+}
+
+@NgModule({schemas: [CUSTOM_ELEMENTS_SCHEMA], declarations: [CompUsingCustomElements]})
+export class ModuleUsingCustomElements {
+}