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:

从由 php -S 调用的 PHP 8.3 内置服务器命令路径开始，跟踪请求日志和应用程序错误的输出方式。定义预期的日志级别过滤和 stdout/stderr 行为，然后添加覆盖测试，展示选定的消息会被过滤，并且标准日志与错误相分离。