Add render graph proof of concept and refactor graphics

Implemented a transient render graph system as a proof of concept, including resource aliasing, pass culling, and typed pass data. Added new project `Ghost.RenderGraph.Concept` targeting `.NET 10.0`.

Refactored graphics-related components:
- Simplified resource state transitions in `RenderingContext`.
- Improved resize handling in `GraphicsTestWindow`.
- Updated `D3D12GraphicsEngine` to streamline frame rendering.
- Enhanced `D3D12ResourceDatabase` and `D3D12SwapChain` for better resource management.

Added detailed documentation:
- `ALIASING.md` explains resource aliasing techniques.
- `API_DESIGN.md` outlines the render graph API design.

Updated solution to include the new render graph project.

Ghost.RenderGraph.Concept/ResourceState.cs

@@ -0,0 +1,21 @@
+namespace Ghost.RenderGraph.Concept;
+
+[Flags]
+public enum ResourceState
+{
+    Undefined = 0,
+    RenderTarget = 1 << 0,
+    DepthWrite = 1 << 1,
+    DepthRead = 1 << 2,
+    ShaderResource = 1 << 3,
+    UnorderedAccess = 1 << 4,
+    CopySource = 1 << 5,
+    CopyDest = 1 << 6,
+    Present = 1 << 7
+}
+
+public enum BarrierType
+{
+    Transition,  // Regular state transition
+    Aliasing     // Aliasing barrier (resource is being reused)
+}