[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/abstract/progress.cpp

@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "progress.h"
+
+namespace QtCommon::Frontend {
+
+QtProgressDialog::QtProgressDialog(const QString&,
+                                   const QString&,
+                                   int,
+                                   int,
+                                   QObject* parent,
+                                   Qt::WindowFlags)
+    : QObject(parent)
+{}
+
+}