PatchesWidget: Convert Core and UICommon includes into forward declarations

Avoids propagating inclusions through UI headers

Source/Core/DolphinQt2/Config/PatchesWidget.cpp

@@ -11,9 +11,14 @@
 #include "Common/FileUtil.h"
 #include "Common/IniFile.h"
 #include "Common/StringUtil.h"
+
 #include "Core/ConfigManager.h"
+#include "Core/PatchEngine.h"
+
 #include "DolphinQt2/Config/NewPatchDialog.h"
 
+#include "UICommon/GameFile.h"
+
 PatchesWidget::PatchesWidget(const UICommon::GameFile& game)
     : m_game(game), m_game_id(game.GetGameID()), m_game_revision(game.GetRevision())
 {

Source/Core/DolphinQt2/Config/PatchesWidget.h

@@ -9,13 +9,22 @@
 
 #include <QWidget>
 
-#include "Core/PatchEngine.h"
-#include "UICommon/GameFile.h"
+#include "Common/CommonTypes.h"
+
+namespace PatchEngine
+{
+struct Patch;
+}
 
 class QListWidget;
 class QListWidgetItem;
 class QPushButton;
 
+namespace UICommon
+{
+class GameFile;
+}
+
 class PatchesWidget : public QWidget
 {
 public: