PHP binary path hardcoded

Would it be possible to be able to override path to PHP binary inside this handler, please? Maybe using some ENV variable?
I am using wrapper for PHP 8.5 under WSL1, so PHP_BINARY constant does not return wrapper, but original binary. Therefore I get this error when running composer under PHP 8.5 with Xdebug enabled:

```
PHP Warning: proc_open(): posix_spawn() failed: Exec format error in phar:///usr/local/bin/composer/vendor/composer/xdebug-handler/src/XdebugHandler.php on line 300
PHP Stack trace:
PHP 1. {main}() /usr/local/bin/composer:0
PHP 2. require() /usr/local/bin/composer:29
PHP 3. Composer\XdebugHandler\XdebugHandler->check() phar:///usr/local/bin/composer/bin/composer:43
PHP 4. Composer\XdebugHandler\XdebugHandler->restart($command = [0 => '/usr/bin/php8.5-bin', 1 => '-n', 2 => '-c', 3 => '/tmp/fh3d7t9hgapgdGR3Iik', 4 => '/usr/local/bin/composer']) phar:///usr/local/bin/composer/vendor/composer/xdebug-handler/src/XdebugHandler.php:149
PHP 5. Composer\XdebugHandler\XdebugHandler->doRestart($command = [0 => '/usr/bin/php8.5-bin', 1 => '-n', 2 => '-c', 3 => '/tmp/fh3d7t9hgapgdGR3Iik', 4 => '/usr/local/bin/composer']) phar:///usr/local/bin/composer/vendor/composer/xdebug-handler/src/XdebugHandler.php:274
PHP 6. proc_open($command = [0 => '/usr/bin/php8.5-bin', 1 => '-n', 2 => '-c', 3 => '/tmp/fh3d7t9hgapgdGR3Iik', 4 => '/usr/local/bin/composer'], $descriptor_spec = [], $pipes = NULL) phar:///usr/local/bin/composer/vendor/composer/xdebug-handler/src/XdebugHandler.php:300
```

It would be nice if path to PHP binary could be specified manually here.

Here is relevant part:
https://github.com/composer/xdebug-handler/blob/main/src/XdebugHandler.php#L438

Instead of:
```
$php = [PHP_BINARY];
```

Maybe something like:

```
$php = [getenv('PHP_BINARY') ?: PHP_BINARY];
```

Or some other solution...?

Thanks!

src/XdebugHandler.php の 438 行目付近、再起動コマンドが PHP_BINARY を選択している箇所から始め、その値がプロセスの再起動にどのように渡されるかを追跡します。オーバーライドが指定されていない場合のフォールバックを含め、オーバーライドの動作を定義して文書化し、その後、再起動されたコマンドに設定済みのバイナリが使用されることを確認します。

索引モデルが issue の本文から書いたものです。