[PHP] Add cp method to Universal PHP

[mho22]

Motivation for the change, related issues

Based on this issue

While playing with PHP.wasm, I found out it has a mv method, but no cp method.

Implementation details

Using directly FSHelpers.copyRecursive inside the php.cp() method

Testing Instructions

cp.ts :

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

const php = new PHP(await loadNodeRuntime('8.5'));

php.mkdir('test');

php.chdir('test');

php.writeFile('foo', `<?php echo "File copied successfully";`);

php.cp('foo', 'bar');

const response = await php.runStream({scriptPath: 'bar'});

console.log(await response.stdoutText, php.listFiles('/test'));

Output :

> node cp.ts

File copied successfully [ 'foo', 'bar' ]