Core: Add new Free Look settings and config

Source/Core/Core/FreeLookConfig.h

@@ -0,0 +1,41 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+// IMPORTANT: UI etc should modify the value returned by FreeLook::GetConfig().
+// Free Look code should read from the value returned by FreeLook::GetActiveConfig().
+// The reason for this is to get rid of race conditions etc when the
+// configuration changes in the middle of a frame.
+
+#pragma once
+
+namespace FreeLook
+{
+enum class ControlType : int
+{
+  SixAxis,
+  FPS,
+  Orbital
+};
+
+struct CameraConfig
+{
+  ControlType control_type;
+};
+
+// NEVER inherit from this class.
+struct Config final
+{
+  Config();
+  void Refresh();
+
+  CameraConfig camera_config;
+  bool enabled;
+};
+
+Config& GetConfig();
+const Config& GetActiveConfig();
+
+// Called every frame.
+void UpdateActiveConfig();
+}  // namespace FreeLook