fix(platform-server): read initial location from INITIAL_CONFIG if present

tools/public_api_guard/platform-server/index.d.ts

@@ -1,6 +1,12 @@
 /** @experimental */
 export declare const INITIAL_CONFIG: InjectionToken<PlatformConfig>;
 
+/** @experimental */
+export interface PlatformConfig {
+    document?: string;
+    url?: string;
+}
+
 /** @experimental */
 export declare const platformDynamicServer: (extraProviders?: Provider[]) => PlatformRef;