..channel.*: refactoring out the common AbstractConfigurableWidgets and
ProcessVariableAdaptable, cleaned up the adapterfactory

Change-Id: Iff1937406c4cb3c43656ecc855af78651e1e1c40
Merge branch '3.2.x' of ssh://git@github.com/ControlSystemStudio/cs-studio.git into 3.2.x
..channel.widget: Refactor out PopupMenuUtil

Change-Id: I2fae5f0748d5ce135ff6a609ebeba0eefb6cc6fb