[desktop] More qt_common reorganization (#3916)

Ported from QML branch.

Main "big" change is that EmuThread is now a shared state in QtCommon,
not individually managed/passed around by GRenderWindow and MainWindow.

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3916
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

src/qt_common/util/content.h

@@ -37,9 +37,12 @@ inline const QString GetKeyInstallResultString(FirmwareManager::KeyInstallResult
 }
 
 void InstallFirmware(const QString& location, bool recursive);
-
 QString UnzipFirmwareToTmp(const QString& location);
 
+bool CheckKeys();
+void InstallFirmware();
+void InstallFirmwareZip();
+
 // Keys //
 void InstallKeys();
 
@@ -54,6 +57,9 @@ void ExportDataDir(FrontendCommon::DataManager::DataDir dir, const std::string&
 void ImportDataDir(FrontendCommon::DataManager::DataDir dir, const std::string& user_id = "",
                    std::function<void()> callback = {});
 
+// Loader //
+void configureFilesystemProvider(const std::string& filepath);
+
 // Profiles //
 void FixProfiles();
 } // namespace QtCommon::Content