overlay: create a dedicated thread for polling hotkeys (#864)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Create a new thread that polls for the following hotkeys:

* super exit (both alt+f4 and bound key)
* coin insert
* screenshot

The goal is to make the capture of these more reliable, because before
this PR it wasn't.

## Testing

src/spice2x/hooks/graphics/backends/d3d9/d3d9_backend.cpp

@@ -1522,7 +1522,7 @@ void graphics_d3d9_on_present(
         wintouchemu::update();
     }
 
-    graphics_d3d9_poll_screenshot_hotkey();
+    graphics_poll_screenshot_hotkey();
     graphics_d3d9_process_screenshot_and_capture(device, SUB_SWAP_CHAIN);
 }
 

src/spice2x/hooks/graphics/backends/d3d9/d3d9_screenshot.cpp

@@ -13,13 +13,9 @@
 #endif
 
 #include "avs/game.h"
-#include "games/io.h"
 #include "hooks/graphics/graphics.h"
-#include "launcher/launcher.h"
 #include "misc/clipboard.h"
-#include "misc/eamuse.h"
 #include "overlay/notifications.h"
-#include "overlay/overlay.h"
 #include "util/fileutils.h"
 #include "util/libutils.h"
 #include "util/logging.h"
@@ -240,21 +236,6 @@ static void save_screenshot(
     }
 }
 
-void graphics_d3d9_poll_screenshot_hotkey() {
-    static bool trigger_last = false;
-    auto buttons = games::get_buttons_overlay(eamuse_get_game());
-    if (buttons && (!overlay::OVERLAY || overlay::OVERLAY->hotkeys_triggered()) &&
-            GameAPI::Buttons::getState(RI_MGR, buttons->at(games::OverlayButtons::Screenshot)))
-    {
-        if (!trigger_last) {
-            graphics_screenshot_trigger();
-        }
-        trigger_last = true;
-    } else {
-        trigger_last = false;
-    }
-}
-
 static std::optional<BackbufferCopy> acquire_backbuffer_copy(
     IDirect3DDevice9 *device, IDirect3DSwapChain9 *sub_swap_chain, int screen) {
 

src/spice2x/hooks/graphics/backends/d3d9/d3d9_screenshot.h

@@ -2,8 +2,6 @@
 
 #include <d3d9.h>
 
-void graphics_d3d9_poll_screenshot_hotkey();
-
 void graphics_d3d9_process_screenshot_and_capture(
         IDirect3DDevice9 *device,
         IDirect3DSwapChain9 *sub_swap_chain);