[12.x]feat: Support custom response without modifying the exception handler

[chuoke]

This PR changes Handler::prepareJsonResponse() to use response()->json() instead of new JsonResponse() directly, ensuring consistency when developers customize the ResponseFactory.

Problem

When developers extend ResponseFactory to customize JSON response behavior (e.g., adding custom headers, wrapping response data, or using a custom JsonResponse subclass), the customization applies everywhere EXCEPT in exception responses, because Handler::prepareJsonResponse() directly instantiates JsonResponse.

Solution

We have 3 ways to maintain consistency.

• Customize the exception handler response
• Enable prepareJsonResponse support callback like the shouldReturnJson method
• Make exception handler use response factory (this PR)

Use the response()->json() helper, which respects custom ResponseFactory implementations.

For example, we customized the JSON response like this:

$this->app->singleton(ResponseFactoryContract::class, function ($app) {
            return new class($app['view'], $app['redirect']) extends ResponseFactory
            {
                public function json($data = [], $status = 200, array $headers = [], $options = 0)
                {
                    $msg = $data['message'] ?? $data['msg'] ?? null;
                    if ($msg) {
                        unset($data['message']);
                        $wrapData = [
                            'msg' => $msg,
                            'success' => $status >= 200 && $status < 300,
                        ] + $data;
                    } else {
                        $wrapData = [
                            'msg' => 'success',
                            'success' => true,
                            'data' => $data,
                        ];
                    }

                    return new JsonResponse($wrapData, 200, $headers, $options);
                }
            };
        });

Before PR, the exception response:

{
    "message": "Server Error"
}

We can see that did not use our customized JSON format.

After PR:

{
    "msg": "Server Error",
    "success": false
}

[taylorotwell]

Bunch of weird formatting / ordering changes on namespaces in the test.