Remove allowUnknownExtensionConfig option from frontend app APIs

The `allowUnknownExtensionConfig` option was unused in practice — unknown
extension config was always reported via the error collector regardless of
the flag. For `createSpecializedApp`, unknown extension config is now always
included in the returned errors. For `createApp`, it is handled as a
console warning via `maybeCreateErrorPage`.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

packages/frontend-app-api/report.api.md

@@ -169,7 +169,6 @@ export type CreateSpecializedAppOptions = {
   bindRoutes?(context: { bind: CreateAppRouteBinder }): void;
   advanced?: {
     apis?: ApiHolder;
-    allowUnknownExtensionConfig?: boolean;
     extensionFactoryMiddleware?:
       | ExtensionFactoryMiddleware
       | ExtensionFactoryMiddleware[];

packages/frontend-app-api/src/wiring/createSpecializedApp.tsx

@@ -255,17 +255,6 @@ export type CreateSpecializedAppOptions = {
      */
     apis?: ApiHolder;
 
-    /**
-     * If set to true, the system will silently accept and move on if
-     * encountering config for extensions that do not exist. The default is to
-     * reject such config to help catch simple mistakes.
-     *
-     * This flag can be useful in some scenarios where you have a dynamic set of
-     * extensions enabled at different times, but also increases the risk of
-     * accidentally missing e.g. simple typos in your config.
-     */
-    allowUnknownExtensionConfig?: boolean;
-
     /**
      * Applies one or more middleware on every extension, as they are added to
      * the application.