Feature/python action events

[schuellc-nvidia]

Description

This PR makes Python actions fully compatible with the UMIM event architecture. Python actions can now be used for fully parallel tasks. They now support:

• ActionStarted events that indicated the start of an action
• StopAction event to stop a running action
• ChangeAction events to update running actions
• ActionUpdated events to feedback information from running actions
• ActionFinished events also in the case of canceled or failed actions

Furthermore, the Colang 2 runtime.py is refactored and simplified. More unit tests are added and various related bugs are fixed.