GH-1795 add terminal launch option to use a specific Minecraft profile

Used like this:
```
./MultiMC --launch 1.17.1 --profile MultiMCTest --server mc.hypixel.net
```

launcher/LauncherMessage.cpp

@@ -0,0 +1,31 @@
+#include "LauncherMessage.h"
+
+#include <QJsonDocument>
+#include <QJsonObject>
+
+void LauncherMessage::parse(const QByteArray & input) {
+    auto doc = QJsonDocument::fromBinaryData(input);
+    auto root = doc.object();
+
+    command = root.value("command").toString();
+    args.clear();
+
+    auto parsedArgs = root.value("args").toObject();
+    for(auto iter = parsedArgs.begin(); iter != parsedArgs.end(); iter++) {
+        args[iter.key()] = iter.value().toString();
+    }
+}
+
+QByteArray LauncherMessage::serialize() {
+    QJsonObject root;
+    root.insert("command", command);
+    QJsonObject outArgs;
+    for (auto iter = args.begin(); iter != args.end(); iter++) {
+        outArgs[iter.key()] = iter.value();
+    }
+    root.insert("args", outArgs);
+
+    QJsonDocument out;
+    out.setObject(root);
+    return out.toBinaryData();
+}