Screenshot functionality Added

Added a screenshot functionality based on this pr https://github.com/xenia-project/xenia/pull/2074 and added some minor adjustments.

GUI wise, "take screenshot" is under the Display menu and the keyboard shortcut to take it is F10

The screenshots folder will save to where xenia.exe or xenia_canary.exe is located. As for save paths, it will only use the id of the game due to illegal characters in some titles.

src/xenia/app/emulator_window.h

@@ -87,6 +87,11 @@ class EmulatorWindow {
   void ToggleFullscreen();
   void SetInitializingShaderStorage(bool initializing);
 
+  void TakeScreenshot();
+  void ExportScreenshot(const xe::ui::RawImage& image);
+  void SaveImage(const std::filesystem::path& path,
+                 const xe::ui::RawImage& image);
+
   // Types of button functions for hotkeys.
   enum class ButtonFunctions {
     ToggleFullscreen,