Add Fallback Region to configuration menu

Fallback Region
A user-selected fallback to use instead of the default PAL

This is used for unknown region or region free titles to give them
the ability to force region to use. This replaces the current fallback region
of PAL. This can be useful if a user is trying to play a region free
tilte that is originally NTSC and expects to be run at NTSC speeds. This
may be done when a user attempts to dump a WAD of their own without
understanding the settings they have chosen, or could be an intentional
decision by a developer of a ROM hack that can be injected into a
Virtual Console WAD.

Remove using System Menu region being checked in GetFallbackRegion

Use DiscIO::Region instead of std::String for fallback

Add explanation text for Fallback Region

Source/Core/Core/Config/MainSettings.cpp

@@ -12,6 +12,7 @@
 #include "Core/HW/Memmap.h"
 #include "Core/HW/SI/SI_Device.h"
 #include "Core/PowerPC/PowerPC.h"
+#include "DiscIO/Enums.h"
 #include "VideoCommon/VideoBackendBase.h"
 
 namespace Config
@@ -106,6 +107,8 @@ const Info<std::string> MAIN_PERF_MAP_DIR{{System::Main, "Core", "PerfMapDir"},
 const Info<bool> MAIN_CUSTOM_RTC_ENABLE{{System::Main, "Core", "EnableCustomRTC"}, false};
 // Default to seconds between 1.1.1970 and 1.1.2000
 const Info<u32> MAIN_CUSTOM_RTC_VALUE{{System::Main, "Core", "CustomRTCValue"}, 946684800};
+const Info<DiscIO::Region> MAIN_FALLBACK_REGION{{System::Main, "Core", "FallbackRegion"},
+                                                DiscIO::Region::NTSC_J};
 const Info<bool> MAIN_AUTO_DISC_CHANGE{{System::Main, "Core", "AutoDiscChange"}, false};
 const Info<bool> MAIN_ALLOW_SD_WRITES{{System::Main, "Core", "WiiSDCardAllowWrites"}, true};
 const Info<bool> MAIN_ENABLE_SAVESTATES{{System::Main, "Core", "EnableSaveStates"}, false};

Source/Core/Core/Config/MainSettings.h

@@ -7,6 +7,7 @@
 #include <string>
 
 #include "Common/Config/Config.h"
+#include "DiscIO/Enums.h"
 
 namespace PowerPC
 {
@@ -88,6 +89,7 @@ extern const Info<u32> MAIN_CUSTOM_RTC_VALUE;
 extern const Info<bool> MAIN_AUTO_DISC_CHANGE;
 extern const Info<bool> MAIN_ALLOW_SD_WRITES;
 extern const Info<bool> MAIN_ENABLE_SAVESTATES;
+extern const Info<DiscIO::Region> MAIN_FALLBACK_REGION;
 
 // Main.DSP