New Module: InjectMessages

This MR adds a new module which doesn't implement any useful algorithm or physics model, but just generates objects of all types, e.g. DepositedCharge objects at random positions in the sensor.

This module is meant for testing the framework as it allows to generate input for any other module without building a full simulation chain as sometimes necessary for e.g. digitization modules.

This certainly isn't the final version but should be fine as dev module for now.