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:

php -S によって呼び出される PHP 8.3 組み込みサーバーのコマンドパスから開始し、リクエストログとアプリケーションエラーがどのように出力されるかを追跡します。想定されるログレベルによるフィルタリングと stdout/stderr の動作を定義し、選択したメッセージがフィルタリングされ、標準ログとエラーが分離されることを示すテストカバレッジを追加します。