Draft: XDebug support via dlopen - #831

…#2326)

## Motivation for the change

This is a pull request to dynamically load Xdebug in `@php-wasm` Node
ASYNCIFY.

[Roadmap](#2315)

## Related issues and pull requests

Relative to XDebug

- #2248
- #314
- #2288
- #831

Relative to dynamic library

- #89
- #2290
- #673

## Implementation details

Additional steps for asyncify are implemented : 

- new nx commands
- new `WITH_JSPI` and `WITH_DEBUG` arguments in Xdebug Dockerfile
- new `xdebug.so` files are compiled and dynamically loaded

## Zend extensions and PHP versions
> [!IMPORTANT]  
> Each version of PHP requires its own version of Xdebug because each
version of PHP has a specific Zend Engine API version. Consequently,
each version of Xdebug is designed to be compatible with a particular
Zend Engine API version.

Example using PHP `8.2` with Xdebug `8.3` :

```
Xdebug requires Zend Engine API version 420230831.
The Zend Engine API version 420220829 which is installed, is outdated.
 ```


## Testing Instructions

Two files are needed. A PHP file to test the step debugger. A JS file to run PHP 8.4 node ASYNCIFY.

`php/xdebug.php`

```php
<?php

$test = 42; // Set a breakpoint on this line

echo "Hello Xdebug World\n";
```


`scripts/node.js`

```javascript
import { PHP } from '@php-wasm/universal';
import { loadNodeRuntime } from '@php-wasm/node';


const php = new PHP( await loadNodeRuntime( '8.4', { withXdebug : true }
) );

await php.runStream( { scriptPath : `php/xdebug.php` } );
```


To achieve the test, you first need to start debugging [ with F5 or Run > Start debugging in VSCode ], then run :

```bash
node scripts/node.js
```