build: replace @types/trusted-types dep with minimal type defs (#39211)

The @types/trusted-types type definitions are currently imported in
types.d.ts, which causes them to eventually be imported in core.d.ts.
This forces anyone compiling against @angular/core to provide the
@types/trusted-types package in their compilation unit, which we don't
want.

To address this, get rid of the @types/trusted-types and instead import
a minimal version of the Trusted Types type definitions directly into
Angular's codebase.

Update the existing references to Trusted Types to point to the new
definitions.

PR Close #39211

packages/core/src/util/security/trusted_type_defs.ts

@@ -0,0 +1,50 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+/**
+ * @fileoverview
+ * While Angular only uses Trusted Types internally for the time being,
+ * references to Trusted Types could leak into our core.d.ts, which would force
+ * anyone compiling against @angular/core to provide the @types/trusted-types
+ * package in their compilation unit.
+ *
+ * Until https://github.com/microsoft/TypeScript/issues/30024 is resolved, we
+ * will keep Angular's public API surface free of references to Trusted Types.
+ * For internal and semi-private APIs that need to reference Trusted Types, the
+ * minimal type definitions for the Trusted Types API provided by this module
+ * should be used instead.
+ *
+ * Adapted from
+ * https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/trusted-types/index.d.ts
+ * but restricted to the API surface used within Angular.
+ */
+
+export type TrustedHTML = {
+  __brand__: 'TrustedHTML'
+};
+export type TrustedScript = {
+  __brand__: 'TrustedScript'
+};
+export type TrustedScriptURL = {
+  __brand__: 'TrustedScriptURL'
+};
+
+export interface TrustedTypePolicyFactory {
+  createPolicy(policyName: string, policyOptions: {
+    createHTML?: (input: string) => string,
+    createScript?: (input: string) => string,
+    createScriptURL?: (input: string) => string,
+  }): TrustedTypePolicy;
+  getAttributeType(tagName: string, attribute: string): string|null;
+}
+
+export interface TrustedTypePolicy {
+  createHTML(input: string): TrustedHTML;
+  createScript(input: string): TrustedScript;
+  createScriptURL(input: string): TrustedScriptURL;
+}

packages/core/src/util/security/trusted_types.ts

@@ -17,6 +17,7 @@
  */
 
 import {global} from '../global';
+import {TrustedHTML, TrustedScript, TrustedScriptURL, TrustedTypePolicy, TrustedTypePolicyFactory} from './trusted_type_defs';
 
 /**
  * The Trusted Types policy, or null if Trusted Types are not