shader: Initial recompiler work

src/shader_recompiler/environment.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "common/common_types.h"
+
+namespace Shader {
+
+class Environment {
+public:
+    virtual ~Environment() = default;
+
+    [[nodiscard]] virtual u64 ReadInstruction(u32 address) const = 0;
+};
+
+} // namespace Shader