ci: move public-api goldens to goldens directory (#35768)

Moves the public api .d.ts files from tools/public_api_guard to
goldens/public-api.

Additionally, provides a README in the goldens directory and a script
assist in testing the current state of the repo against the goldens as
well as a command for accepting all changes to the goldens in a single
command.

PR Close #35768

goldens/public-api/service-worker/service-worker.d.ts

@@ -0,0 +1,59 @@
+export declare class ServiceWorkerModule {
+    static register(script: string, opts?: SwRegistrationOptions): ModuleWithProviders<ServiceWorkerModule>;
+}
+
+export declare class SwPush {
+    get isEnabled(): boolean;
+    readonly messages: Observable<object>;
+    readonly notificationClicks: Observable<{
+        action: string;
+        notification: NotificationOptions & {
+            title: string;
+        };
+    }>;
+    readonly subscription: Observable<PushSubscription | null>;
+    constructor(sw: ɵangular_packages_service_worker_service_worker_a);
+    requestSubscription(options: {
+        serverPublicKey: string;
+    }): Promise<PushSubscription>;
+    unsubscribe(): Promise<void>;
+}
+
+export declare abstract class SwRegistrationOptions {
+    enabled?: boolean;
+    registrationStrategy?: string | (() => Observable<unknown>);
+    scope?: string;
+}
+
+export declare class SwUpdate {
+    readonly activated: Observable<UpdateActivatedEvent>;
+    readonly available: Observable<UpdateAvailableEvent>;
+    get isEnabled(): boolean;
+    constructor(sw: ɵangular_packages_service_worker_service_worker_a);
+    activateUpdate(): Promise<void>;
+    checkForUpdate(): Promise<void>;
+}
+
+export declare interface UpdateActivatedEvent {
+    current: {
+        hash: string;
+        appData?: Object;
+    };
+    previous?: {
+        hash: string;
+        appData?: Object;
+    };
+    type: 'UPDATE_ACTIVATED';
+}
+
+export declare interface UpdateAvailableEvent {
+    available: {
+        hash: string;
+        appData?: Object;
+    };
+    current: {
+        hash: string;
+        appData?: Object;
+    };
+    type: 'UPDATE_AVAILABLE';
+}