Allow for different AA/AI models in sensing, actuation, and pcal models; understand how gain of AA/AI might propogate through pyDARM

Be more explicit about the AA and AI models used in different parts of pyDARM so that we don't rely on, for example, convenient cancellation in the sensing function measurements. Apply those models correctly in the measurements of sensing and actuation parameters.

The measured AA gain might not be 1.0 and we need to understand how that goes through the PCAL photodiode calibration and then on through the DARM model measurements.

Cross-reference to IIET Ticket https://services.ligo-la.caltech.edu/FRS/show_bug.cgi?id=12642.