qml: add keyboard shortcuts table on system menu

copy-runtime-files.ps1

jami-qt.pro

qml.qrc

src/KeyBoardShortcutKey.qml

src/KeyBoardShortcutTable.qml

src/callwidget.cpp

src/main.cpp

src/mainwindow.cpp

src/mainwindow.h

src/widgethelpers.cpp

src/widgethelpers.h