Developper guide does not give packages for Qt5 System on Ubuntu

Here is the list:

• FindQt5.cmake for qtbase5-dev
• qtmultimedia5-dev for Qt5MultimediaConfig.cmake
• qttools5-dev for Qt5UiToolsConfig.cmake
• qtbase5-private-dev for qmetaobjectbuilder_p.h
• libqt5x11extras5-dev for Qt5X11ExtrasConfig.cmake

migrated from: https://gitlab.kitware.io/ComputerVision/LidarView/issues/33