Refactor resource management and enforce code formatting

Refactored `D3D12ResourceAllocator` to improve maintainability,
introducing new descriptor creation methods, utility functions,
and enhanced resource handling. Added thread safety and proper
disposal logic. Updated `.editorconfig` to enforce consistent
`using` directive sorting and increased max line length.

Revised `BufferUsage` enum in `Common.cs` to include new flags
and reorganized existing ones. Refactored `RenderTargetDesc`
conversion to an instance method. Adjusted `MeshRenderPass`
for consistency and added a parameter to `Execute`.

Minor formatting updates in `ShaderCode.hlsl` and cleanup of
unused directives in `D3D12Utility.cs`. Overall, these changes
enhance readability, maintainability, and functionality.

.editorconfig

@@ -2,6 +2,6 @@
 csharp_new_line_before_open_brace = all
 csharp_preserve_single_line_statements = true
 csharp_preserve_single_line_blocks = true
-dotnet_sort_system_directives_first = false
-dotnet_separate_import_directive_groups = false
+dotnet_sort_system_directives_first = true
+dotnet_separate_import_directive_groups = true
 max_line_length = 400