Rework server-side entity spawning

[tornac1234]

• Fix fragment spawning
• Fix nested structure spawning (e.g a bottle of water spawns inside of a supply crate inside of a wreck)
• Introduce an uniform UnityEngine.Random like generation for floats (see XORRandom)
• Add a button to teleport to the selected object in the Scene debugger
• Implement empty objects (like lights and things which we apparently ignored in the past but therefore didn't spawn)
• Fix Crashes (the explosive fishes) postponed to a further PR which will also fix vehicle constructors and add finitions to the entity system
• Handle sub-spawners monobehaviours in placeholders groups

[Measurity]

Just a minor quick code review for now so I can look at PR 2090

[tornac1234]

I'll wait for further reviews to push the mentionned changes

[Measurity]

Minor thing: moving the PrefabPlaceholderEntity in WorldPersistenceTest to the correct switch (inside WorldEntity condition) and unit test will succeed.

[Jannify]

One test is failing still. Can be fixed with the comment in SerializedWorldEntitySpawner.cs and also this change in NitroxClient.GameLogic.Spawning.WorldEntities.CrashEntitySpawner:

private static readonly Quaternion spawnRotation = new(-0.7f, 0f, 0f, 0.7f); // Equal to Quaternion.Euler(-90f, 0f, 0f)```

Test fixed