Implement signal generation for partially depleted detectors

[fhagemann]

Literature:

• https://doi.org/10.1016/S0168-9002(02)01169-5
• https://doi.org/10.1016/j.nima.2004.07.129
• https://doi.org/10.1016/j.nima.2019.06.056 !!
• https://indico.cern.ch/event/812761/sessions/314742/#20190613