HotkeyManager: Move HotkeyGroupInfo struct into the cpp file

This is only ever used internally. Also change the std::string name over
to a const char*, so that we don't need to potentially allocate anything
on the heap at immediate runtime.

Source/Core/Core/HotkeyManager.cpp

@@ -239,7 +239,14 @@ void Shutdown()
 }
 }
 
-const std::array<HotkeyGroupInfo, NUM_HOTKEY_GROUPS> groups_info = {
+struct HotkeyGroupInfo
+{
+  const char* name;
+  Hotkey first;
+  Hotkey last;
+};
+
+constexpr std::array<HotkeyGroupInfo, NUM_HOTKEY_GROUPS> groups_info = {
     {{_trans("General"), HK_OPEN, HK_EXIT},
      {_trans("Volume"), HK_VOLUME_DOWN, HK_VOLUME_TOGGLE_MUTE},
      {_trans("Emulation Speed"), HK_DECREASE_EMULATION_SPEED, HK_TOGGLE_THROTTLE},

Source/Core/Core/HotkeyManager.h

@@ -180,13 +180,6 @@ enum HotkeyGroup : int
   NUM_HOTKEY_GROUPS,
 };
 
-struct HotkeyGroupInfo
-{
-  std::string name;
-  Hotkey first;
-  Hotkey last;
-};
-
 struct HotkeyStatus
 {
   u32 button[NUM_HOTKEY_GROUPS];