TAS Input: Enable hotkeys and controller input when Input has focus

Enable emulator hotkeys and controller input (when that option is
enabled) when a TAS Input window has focus, as if it was the render
window instead.  This allows TASers to use frame advance and the like
without having to switch the focused window or disabling Hotkeys Require
Window Focus which also picks up keypresses while other apps are active.

Cursor updates are disabled when the TAS Input window has focus, as
otherwise the Wii IR widget (and anything else controlled by the mouse)
becomes unusable. The cursor continues to work normally when the render
window has focus.

Source/Core/Core/Core.cpp

@@ -1073,7 +1073,8 @@ void UpdateInputGate(bool require_focus, bool require_full_focus)
 {
   // If the user accepts background input, controls should pass even if an on screen interface is on
   const bool focus_passes =
-      !require_focus || (Host_RendererHasFocus() && !Host_UIBlocksControllerState());
+      !require_focus ||
+      ((Host_RendererHasFocus() || Host_TASInputHasFocus()) && !Host_UIBlocksControllerState());
   // Ignore full focus if we don't require basic focus
   const bool full_focus_passes =
       !require_focus || !require_full_focus || (focus_passes && Host_RendererHasFullFocus());

Source/Core/Core/Host.h

@@ -53,6 +53,7 @@ bool Host_UIBlocksControllerState();
 bool Host_RendererHasFocus();
 bool Host_RendererHasFullFocus();
 bool Host_RendererIsFullscreen();
+bool Host_TASInputHasFocus();
 
 void Host_Message(HostMessageID id);
 void Host_PPCSymbolsChanged();