[desktop] Port some QtCommon changes from QML branch (#3703)

- Linker now resolves implementation differences
- Remove unneeded ifdefs
- Better abstractions overall

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3703
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/qt_common/util/content.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #ifndef QT_CONTENT_UTIL_H
@@ -13,7 +13,7 @@
 namespace QtCommon::Content {
 
 //
-bool CheckGameFirmware(u64 program_id, QObject *parent);
+bool CheckGameFirmware(u64 program_id);
 
 enum class FirmwareInstallResult {
     Success,