Unify ISOFile (wx) with GameFile (Qt) and put it in UICommon

The original reason I wanted to do this was so that we can replace
the Android-specific code with this in the future, but of course,
just deduplicating between DolphinWX and DolphinQt2 is nice too.

Fixes:

- DolphinQt2 showing the wrong size for split WBFS disc images.

- DolphinQt2 being case sensitive when checking if a file is a DOL/ELF.

- DolphinQt2 not detecting when a Wii banner has become available
after the game list cache was created.

Removes:

- DolphinWX's ability to load PNGs as custom banners. But it was
already rather broken (see https://bugs.dolphin-emu.org/issues/10365
and https://bugs.dolphin-emu.org/issues/10366). The reason I removed
this was because PNG decoding relied on wx code and we don't have any
good non-wx/Qt code for loading PNG files right now (let's not use
SOIL), but we should be able to use libpng directly to implement PNG
loading in the future.

- DolphinQt2's ability to ignore a cached game if the last modified
time differs. We currently don't have a non-wx/Qt way to get the time.

Source/Core/DolphinQt2/Config/InfoWidget.h

@@ -4,20 +4,23 @@
 
 #pragma once
 
+#include <string>
+
 #include <QWidget>
 
-#include "DolphinQt2/GameList/GameFile.h"
+#include "UICommon/GameFile.h"
 
 class QComboBox;
 class QGroupBox;
-class QTextEdit;
 class QLineEdit;
+class QPixmap;
+class QTextEdit;
 
 class InfoWidget final : public QWidget
 {
   Q_OBJECT
 public:
-  explicit InfoWidget(const GameFile& game);
+  explicit InfoWidget(const UICommon::GameFile& game);
 
 private:
   void ComputeChecksum();
@@ -26,13 +29,13 @@ private:
 
   QGroupBox* CreateBannerDetails();
   QGroupBox* CreateISODetails();
-  QLineEdit* CreateValueDisplay() { return CreateValueDisplay(QStringLiteral("")); };
   QLineEdit* CreateValueDisplay(const QString& value);
+  QLineEdit* CreateValueDisplay(const std::string& value = "");
   QWidget* CreateChecksumComputer();
   void CreateLanguageSelector();
-  QWidget* CreateBannerGraphic();
+  QWidget* CreateBannerGraphic(const QPixmap& image);
 
-  GameFile m_game;
+  UICommon::GameFile m_game;
   QLineEdit* m_checksum_result;
   QComboBox* m_language_selector;
   QLineEdit* m_long_name;