QmlDesigner: enable Qt Quick Designer just for qml files
QmlDesigner: enable Qt Quick Designer just for qml files

No .js files in the visual designer.

Task-number: QTCREATORBUG-4166
Reviewed-by: Kai Koehne

ostash/qt-creator-i18n-uk,azat/qtcreator,syntheticpp/qt-creator,omniacreator/qtcreator,amyvmiwei/qt-creator,pcacjr/qt-creator,duythanhphan/qt-creator,richardmg/qtcreator,farseerri/git_code,AltarBeastiful/qt-creator,jonnor/qt-creator,malikcjm/qtcreator,KDE/android-qt-creator,richardmg/qtcreator,maui-packages/qt-creator,pcacjr/qt-creator,darksylinc/qt-creator,azat/qtcreator,renatofilho/QtCreator,bakaiadam/collaborative_qt_creator,hdweiss/qt-creator-visualizer,azat/qtcreator,farseerri/git_code,maui-packages/qt-creator,hdweiss/qt-creator-visualizer,malikcjm/qtcreator,azat/qtcreator,amyvmiwei/qt-creator,danimo/qt-creator,ostash/qt-creator-i18n-uk,KDE/android-qt-creator,KDAB/KDAB-Creator,Distrotech/qtcreator,colede/qtcreator,ostash/qt-creator-i18n-uk,Distrotech/qtcreator,hdweiss/qt-creator-visualizer,dmik/qt-creator-os2,azat/qtcreator,jonnor/qt-creator,richardmg/qtcreator,renatofilho/QtCreator,xianian/qt-creator,omniacreator/qtcreator,syntheticpp/qt-creator,AltarBeastiful/qt-creator,azat/qtcreator,danimo/qt-creator,duythanhphan/qt-creator,omniacreator/qtcreator,maui-packages/qt-creator,duythanhphan/qt-creator,maui-packages/qt-creator,omniacreator/qtcreator,kuba1/qtcreator,darksylinc/qt-creator,jonnor/qt-creator,darksylinc/qt-creator,syntheticpp/qt-creator,malikcjm/qtcreator,kuba1/qtcreator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,KDE/android-qt-creator,duythanhphan/qt-creator,malikcjm/qtcreator,KDAB/KDAB-Creator,syntheticpp/qt-creator,KDE/android-qt-creator,Distrotech/qtcreator,maui-packages/qt-creator,renatofilho/QtCreator,colede/qtcreator,syntheticpp/qt-creator,hdweiss/qt-creator-visualizer,bakaiadam/collaborative_qt_creator,xianian/qt-creator,jonnor/qt-creator,duythanhphan/qt-creator,KDAB/KDAB-Creator,duythanhphan/qt-creator,danimo/qt-creator,dmik/qt-creator-os2,xianian/qt-creator,darksylinc/qt-creator,malikcjm/qtcreator,AltarBeastiful/qt-creator,danimo/qt-creator,kuba1/qtcreator,dmik/qt-creator-os2,KDAB/KDAB-Creator,maui-packages/qt-creator,renatofilho/QtCreator,farseerri/git_code,pcacjr/qt-creator,kuba1/qtcreator,danimo/qt-creator,dmik/qt-creator-os2,kuba1/qtcreator,omniacreator/qtcreator,amyvmiwei/qt-creator,Distrotech/qtcreator,farseerri/git_code,AltarBeastiful/qt-creator,AltarBeastiful/qt-creator,farseerri/git_code,duythanhphan/qt-creator,pcacjr/qt-creator,richardmg/qtcreator,hdweiss/qt-creator-visualizer,xianian/qt-creator,KDAB/KDAB-Creator,kuba1/qtcreator,xianian/qt-creator,malikcjm/qtcreator,maui-packages/qt-creator,ostash/qt-creator-i18n-uk,amyvmiwei/qt-creator,colede/qtcreator,danimo/qt-creator,hdweiss/qt-creator-visualizer,kuba1/qtcreator,syntheticpp/qt-creator,martyone/sailfish-qtcreator,farseerri/git_code,jonnor/qt-creator,ostash/qt-creator-i18n-uk,renatofilho/QtCreator,xianian/qt-creator,martyone/sailfish-qtcreator,pcacjr/qt-creator,pcacjr/qt-creator,amyvmiwei/qt-creator,renatofilho/QtCreator,farseerri/git_code,Distrotech/qtcreator,Distrotech/qtcreator,colede/qtcreator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,kuba1/qtcreator,dmik/qt-creator-os2,AltarBeastiful/qt-creator,omniacreator/qtcreator,syntheticpp/qt-creator,colede/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,AltarBeastiful/qt-creator,KDE/android-qt-creator,bakaiadam/collaborative_qt_creator,amyvmiwei/qt-creator,darksylinc/qt-creator,ostash/qt-creator-i18n-uk,kuba1/qtcreator,AltarBeastiful/qt-creator,dmik/qt-creator-os2,darksylinc/qt-creator,KDE/android-qt-creator,malikcjm/qtcreator,richardmg/qtcreator,Distrotech/qtcreator,darksylinc/qt-creator,richardmg/qtcreator,dmik/qt-creator-os2,xianian/qt-creator,KDE/android-qt-creator,bakaiadam/collaborative_qt_creator,martyone/sailfish-qtcreator,omniacreator/qtcreator,ostash/qt-creator-i18n-uk,martyone/sailfish-qtcreator,bakaiadam/collaborative_qt_creator,darksylinc/qt-creator,xianian/qt-creator,danimo/qt-creator,danimo/qt-creator,farseerri/git_code,martyone/sailfish-qtcreator,KDE/android-qt-creator,colede/qtcreator,jonnor/qt-creator,colede/qtcreator,KDAB/KDAB-Creator,amyvmiwei/qt-creator,pcacjr/qt-creator,bakaiadam/collaborative_qt_creator,bakaiadam/collaborative_qt_creator,richardmg/qtcreator