Refactor ECS core, improve thread safety, add tests

- Switch Scene IDs to ushort, update invalid value logic
- Add thread safety to SceneManager and ComponentRegistry
- Add GHOST_ZERO_INIT_COMPONENT define for editor configs
- Update mesh header counts to use int, not uint
- Add Collect methods for archetype/component cleanup
- Add With/Without/AsView to ComponentSet for easier use
- Refactor World creation/destruction, version handling
- Refactor ResourceStreamingContext to use init-only props
- Add unit tests for entity queries and world lifecycle
- Minor code cleanups and formatting fixes

src/Test/Ghost.UnitTest/ECS/WorldTests.cs

@@ -0,0 +1,28 @@
+using Ghost.Entities;
+
+namespace Ghost.UnitTest.ECS;
+
+[TestClass]
+[DoNotParallelize]
+public class WorldTests
+{
+    [TestMethod]
+    public void CreateWorld()
+    {
+        using var world = World.Create();
+        Assert.IsNotNull(world);
+    }
+
+    [TestMethod]
+    public void AddEntityThenClearWorld()
+    {
+        using var world =  World.Create();
+        Assert.IsNotNull(world);
+
+        world.EntityManager.CreateEntity();
+        Assert.AreEqual(1, world.EntityManager.EntityCount);
+
+        world.Clear(default);
+        Assert.AreEqual(0, world.EntityManager.EntityCount);
+    }
+}