WebAssembly: Drop run config inheritance from CustomExecutable

Also, auto-detect free port.

Change-Id: I377956ef20a928f1877d702162792e7cae75a202
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/webassembly/webassemblyplugin.cpp

@@ -36,9 +36,6 @@
 
 #include <projectexplorer/devicesupport/devicemanager.h>
 
-#include <QMenu>
-#include <QMessageBox>
-
 namespace WebAssembly {
 namespace Internal {
 
@@ -49,6 +46,7 @@ public:
     WebAssemblyDeviceFactory deviceFactory;
     WebAssemblyQtVersionFactory qtVersionFactory;
     EmrunRunConfigurationFactory emrunRunConfigurationFactory;
+    EmrunRunWorkerFactory emrunRunWorkerFactory;
 };
 
 static WebAssemblyPluginPrivate *dd = nullptr;