GPU: Implemented a gpu macro interpreter.

The Ryujinx macro interpreter and envydis were used as reference.

Macros are programs that are uploaded by the games during boot and can later be called by writing to their method id in a GPU command buffer.

src/video_core/engines/maxwell_3d.cpp

@@ -386,5 +386,10 @@ std::vector<Texture::FullTextureInfo> Maxwell3D::GetStageTextures(Regs::ShaderSt
     return textures;
 }
 
+u32 Maxwell3D::GetRegisterValue(u32 method) const {
+    ASSERT_MSG(method < Regs::NUM_REGS, "Invalid Maxwell3D register");
+    return regs.reg_array[method];
+}
+
 } // namespace Engines
 } // namespace Tegra