feat(2.9): deprecate ResetDatabase trait

[nikophil]

⚠️ This PR is on top of #968 - please only review the two last commits

[nikophil]

@HypeMC, just for you to know:

now we're deprecating the usage of ResetDatabase trait in favor of an attribute + usage of the PHPUnit extension, I had errors ServiceNotFoundException: The "kernel" service is synthetic, it needs to be set at boot time before it can be used. in the database reset testsuite.

Because this currently needs to work with and without the ResetDatabase trait, the only solution I found was to check if the extension is enabled.

Don't hesitate if you have another idea. Anyway, this ugly stuff will be removed in Foundry 3

[HypeMC]

@nikophil Hello, thank you for the heads-up. I've tested this branch, and unfortunately, this change seems to bring back the original issue. I haven't had time to look into it in detail yet, but I'll try to figure it out.

EDIT: Switching to the #[ResetDatabase] attribute does solve the problem.

[HypeMC]

The reason the EarlyBootedKernelWithTraitsTest passes is that it's no longer the first test, so ResetDatabaseManager::hasDatabaseBeenReset is true.
It needs to be false for the test to fail, e.g. try running it individually:

./phpunit tests/Integration/ResetDatabase/EarlyBootedKernelWithTraitsTest.php

Perhaps the before() method could be improved:

#[BeforeClass(10)]
public static function before(): void
{
    $ref = new \ReflectionProperty(ResetDatabaseManager::class, 'hasDatabaseBeenReset');
    $ref->setValue(false);

    self::bootKernel();
}

[nikophil]

@HypeMC I'm not sure what's the best way to fix this: we would need a marker to tell "reset database trait was used" to decide whether to check Configuration::isBooted() in ZenstruckFoundryBundle::boot() method

this becomes overly complex for such a niche bug, moreover that the problem will only occur when using the newly deprecated trait ResetDatabase

I think it will stay this way, unless you have a good idea