Port remaining sidebar actions to qml

resources/qml/RoomList.qml

src/MainWindow.cpp

src/SideBarActions.cpp

src/SideBarActions.h

src/Splitter.cpp

src/Splitter.h

src/UserInfoWidget.cpp

src/UserInfoWidget.h

src/ui/NhekoGlobalObject.cpp

src/ui/NhekoGlobalObject.h