Fix race condition in EvalLoader

[MrMeshok]

When using swoole coroutines with eval loader, where is a possibility to get an error Cannot declare class {class}, because the name is already in use, because coroutines share memory and declared classes.
Can be tested like this

require 'vendor/autoload.php';

readonly class Dto
{
    public function __construct(
        public int $id,
    ) {}
}

$mapper = \AutoMapper\AutoMapper::create();
$data = ['id' => 1];

\Co\run(static function () use ($mapper, $data) {
    for ($i=1; $i < 100_000; $i++) { 
        \Co\go(static fn () => $mapper->map($data, Dto::class));
    }
});

[MrMeshok]

This code block looks a little weird, but there is a reason for this.
At first, it looked like this

while (isset(self::$lockMap[$mapperMetadata->className])) {
    usleep(100000); // 0.1 second
}

if (class_exists($mapperMetadata->className, false)) {
    return;
}

But there is a problem, class_exists gets called every time, but he only needed if lock existed, so I restructured code to first check lock inside if and then start while loop

[joelwurtz]

Not sure you could do that if using the LockFactory, anyway an extra call to class_exists should not be a problem

[joelwurtz]

Indeed, we have done something similar for the FileLoader here #174

Can you use the LockFactory instead of a while loop, like done on this PR ? This way i believe you could use a specific implementation that can handle an event loop for the LockFactory (like one that use this https://www.php.net/manual/fr/class.swoole-lock.php)

Then it will avoid loop + sleep and just block in an async way (allowing you to execute other coroutines)