build: build material-examples with bazel (#13932)

This includes a `genrule` to create the generated `ExampleModule`

tools/example-module/example-module.template

@@ -0,0 +1,36 @@
+/* tslint:disable */
+
+/**
+ ******************************************************************************
+ * DO NOT MANUALLY EDIT THIS FILE. THIS FILE IS AUTOMATICALLY GENERATED.
+ ******************************************************************************
+ */
+
+import {NgModule} from '@angular/core';
+import {FormsModule, ReactiveFormsModule} from '@angular/forms';
+import {CommonModule} from '@angular/common';
+import {ExampleMaterialModule} from './material-module';
+
+${exampleImports}
+
+export interface LiveExample {
+  title: string;
+  component: any;
+  additionalFiles?: string[];
+  selectorName?: string;
+}
+
+export const EXAMPLE_COMPONENTS: {[key: string]: LiveExample} = ${exampleComponents};
+export const EXAMPLE_LIST = ${exampleList}
+
+@NgModule({
+  declarations: EXAMPLE_LIST,
+  entryComponents: EXAMPLE_LIST,
+  imports: [
+    ExampleMaterialModule,
+    FormsModule,
+    ReactiveFormsModule,
+    CommonModule
+  ]
+})
+export class ExampleModule { }