[Qml] Implement activities for Qml applications
Description
Currently, the activities can only be launched in a XML based application. We want to implement the concept for Qml application.
Proposal
Try to use the Activities registry to launch an AppManager instead of an AppConfig.
Update AppManager to define parameters as for the AppConfig (data, view identifier, channels, ...). It will be required to generate unique prefix for object ids.
Implements the Qml version of ::guiQt::editor::SActivityView
. To launch the sub-AppManager.