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/webassemblyrunconfigurationaspects.cpp

@@ -103,12 +103,5 @@ QString WebBrowserSelectionAspect::currentBrowser() const
     return m_currentBrowser;
 }
 
-EffectiveEmrunCallAspect::EffectiveEmrunCallAspect()
-{
-    setLabelText(tr("Effective emrun call:"));
-    setDisplayStyle(BaseStringAspect::TextEditDisplay);
-    setReadOnly(true);
-}
-
 } // namespace Internal
 } // namespace Webassembly