fix(appimage): launch external processes with bundled linker

This ensures that external processes (including our updater and
Minecraft itself) maintain the same compatibility guarantees as the main
binary

Signed-off-by: Seth Flynn <getchoo@tuta.io>

launcher/FileSystem.cpp

@@ -4,6 +4,7 @@
  *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
  *  Copyright (C) 2022 TheKodeToad <TheKodeToad@proton.me>
  *  Copyright (C) 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+ *  Copyright (C) 2025 Seth Flynn <getchoo@tuta.io>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -772,6 +773,34 @@ QString ResolveExecutable(QString path)
     return pathInfo.absoluteFilePath();
 }
 
+std::unique_ptr<QProcess> createProcess(const QString& program, const QStringList& arguments)
+{
+    qDebug() << "Creating process for" << program;
+    auto proc = std::unique_ptr<QProcess>(new QProcess());
+
+#if defined(Q_OS_LINUX)
+    if (DesktopServices::isSelfContained()) {
+        const auto linkerPath = QCoreApplication::applicationFilePath();
+        qDebug() << "Wrapping" << program << "with self-contained linker at" << linkerPath;
+
+        QStringList wrappedArguments;
+        wrappedArguments << "--inhibit-cache" << program;
+        wrappedArguments += arguments;
+
+        proc->setProgram(linkerPath);
+        proc->setArguments(wrappedArguments);
+    } else {
+        proc->setProgram(program);
+        proc->setArguments(arguments);
+    }
+#else
+    proc->setProgram(program);
+    proc->setArguments(arguments);
+#endif
+
+    return proc;
+}
+
 /**
  * Normalize path
  *