Wrapper for execution BASH and python modules

[phracek]

In order to support better module testing,
preupgrade-assistant should deliver a script like preupg-test-check-script which will check, whether
behaviour is fine or not.

[phracek]

This will be handled by different way.
We should use a general wrapper around all our BASH and Python script, we are able to run them without preupg binary.

[bocekm]

@AloisMahdal idea: the wrapper would also add module set API to the path. Module set API = utilities created (for example in the root of a module set) to be shared among modules to avoid duplicity.