Refactor GPU resource management and rendering pipeline

- Introduced `Handle<T>` and `Identifier<T>` for lightweight, strongly-typed resource identifiers.
- Replaced `BitSet` with `UnsafeBitSet` for improved performance and memory safety.
- Refactored `Mesh` and `Material` into `MeshClass` and `MaterialClass` for better GPU resource handling.
- Added `D3D12ResourceDatabase` to centralize GPU resource tracking and lifecycle management.
- Updated `D3D12ShaderCompiler` to load shaders from disk and dynamically populate constant buffers and textures.
- Enhanced `ICommandBuffer` with new upload operations for buffers and textures.
- Refactored `Vertex` struct for simplified memory layout and better performance.
- Updated `MeshBuilder` and rendering logic to align with new resource and shader structures.
- Added `BindlessDescriptor` support to `TextureHandle` and `BufferHandle`.
- Removed unused classes and performed general cleanup.
- Updated unit tests and demos to reflect the new architecture.

Ghost.Graphics/RHI/IResourceAllocator.cs

@@ -4,40 +4,26 @@ namespace Ghost.Graphics.RHI;
 
 public interface IResourceAllocator
 {
-    /// <summary>
-    /// Creates a render target for off-screen rendering
-    /// </summary>
-    /// <param name="desc">Render target description</param>
-    /// <returns>A new render target instance</returns>
-    public IRenderTarget CreateRenderTarget(ref readonly RenderTargetDesc desc, bool tempResource = false);
-
     /// <summary>
     /// Creates a texture resource
     /// </summary>
     /// <param name="desc">Texture description</param>
     /// <returns>A new texture handle point to the resource</returns>
-    public TextureHandle CreateTextureHandle(ref readonly TextureDesc desc, bool tempResource = false);
+    public TextureHandle CreateTexture(ref readonly TextureDesc desc, bool tempResource = false);
 
     /// <summary>
-    /// Creates a texture resource
+    /// Creates a render target for off-screen rendering
     /// </summary>
-    /// <param name="desc">Texture description</param>
-    /// <returns>A new texture instance</returns>
-    public ITexture CreateTexture(ref readonly TextureDesc desc, bool tempResource = false);
+    /// <param name="desc">Render target description</param>
+    /// <returns>A new render target instance</returns>
+    public TextureHandle CreateRenderTarget(ref readonly RenderTargetDesc desc, bool tempResource = false);
 
     /// <summary>
     /// Creates a buffer resource
     /// </summary>
     /// <param name="desc">Buffer description</param>
     /// <returns>A new buffer handle point to the resource</returns>
-    public BufferHandle CreateBufferHandle(ref readonly BufferDesc desc, bool tempResource = false);
-
-    /// <summary>
-    /// Creates a buffer resource
-    /// </summary>
-    /// <param name="desc">Buffer description</param>
-    /// <returns>A new buffer instance</returns>
-    public IBuffer CreateBuffer(ref readonly BufferDesc desc, bool tempResource = false);
+    public BufferHandle CreateBuffer(ref readonly BufferDesc desc, bool tempResource = false);
 
     /// <summary>
     /// Release a resource given its handle