[meta] Add option to FORCE X11 as Graphics Backend (#2820)

* save the option on a external file because settings
  are loaded AFTER Qt window is created and then
  the graphics backend is already applied

Signed-off-by: Caio Oliveira <caiooliveirafarias0@gmail.com>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2820
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>
Co-authored-by: Caio Oliveira <caiooliveirafarias0@gmail.com>
Co-committed-by: Caio Oliveira <caiooliveirafarias0@gmail.com>

src/qt_common/gui_settings.cpp

@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "gui_settings.h"
+#include "common/fs/fs.h"
+#include "common/fs/path_util.h"
+
+namespace FS = Common::FS;
+
+namespace GraphicsBackend {
+
+QString GuiConfigPath() {
+    return QString::fromStdString(FS::PathToUTF8String(FS::GetEdenPath(FS::EdenPath::ConfigDir) / "gui_config.ini"));
+}
+
+void SetForceX11(bool state) {
+    (void)FS::CreateParentDir(GuiConfigPath().toStdString());
+    QSettings(GuiConfigPath(), QSettings::IniFormat).setValue("gui_force_x11", state);
+}
+
+bool GetForceX11() {
+    return QSettings(GuiConfigPath(), QSettings::IniFormat).value("gui_force_x11", false).toBool();
+}
+
+} // namespace GraphicsBackend