video_core: Bringup some basic functionality (#145)

* video_core: Remove hack in rasterizer

* The hack was to skip the first draw as the display buffer had not been created yet and the texture cache couldn't create one itself. With this patch it now can, using the color buffer parameters from registers

* shader_recompiler: Implement attribute loads/stores

* video_core: Add basic vertex, index buffer handling and pipeline caching

* externals: Make xxhash lowercase

src/shader_recompiler/frontend/fetch_shader.h

@@ -0,0 +1,21 @@
+// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <vector>
+#include "common/types.h"
+
+namespace Shader::Gcn {
+
+struct VertexAttribute {
+    u8 semantic;     ///< Semantic index of the attribute
+    u8 dest_vgpr;    ///< Destination VGPR to load first component.
+    u8 num_elements; ///< Number of components to load
+    u8 sgpr_base;    ///< SGPR that contains the pointer to the list of vertex V#
+    u8 dword_offset; ///< The dword offset of the V# that describes this attribute.
+};
+
+std::vector<VertexAttribute> ParseFetchShader(const u32* code);
+
+} // namespace Shader::Gcn