Log Level Filtering for PHP Built-in Server

Description

Hi,
We use the PHP 8.3 built-in server during development, and it has been very helpful. However, there is an excessive amount of stdout output. For every request to resources like images, JS, or CSS files, it logs messages such as Accepted, GET, Closing, etc.

Because of this, it becomes very difficult to see the stdout output or error messages from within the application itself. I couldn't find an option to filter these logs. A feature like loglevel could be helpful to manage this.

For example:
php -S 0.0.0.0:8086 -t ./public --loglevel 4

This would allow filtering logs based on levels (e.g., errors, warnings, info, etc.), making it easier to focus on application-specific outputs during development.

Additionally, the PHP built-in server outputs all logs to stderr, which seems like a bug. Ideally, standard logs should go to stdout and error messages to stderr.

PHP built-in server output like:

Comienza con la ruta del comando del servidor integrado de PHP 8.3 invocada por php -S y rastrea cómo se emiten los registros de solicitudes y los errores de la aplicación. Define el filtrado esperado por nivel de registro y el comportamiento de stdout/stderr; después, añade cobertura que demuestre que los mensajes seleccionados se filtran y que los registros estándar se separan de los errores.