Add the base of java downloading

Signed-off-by: timoreo <contact@timoreo.fr>

launcher/JavaDownloader.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <QString>
+
+namespace JavaDownloader {
+    /*Downloads the java to the runtimes folder*/
+    void downloadJava(bool isLegacy, const QString& OS);
+}