Allow for use of the new 524k ADC sensing chain at LHO

Essentially, we need to allow for the possibility that the anti_aliasing_rate_string and anti_aliasing_method parameters are either not given or are a list of empty strings. In that case, just pass back a unity transfer function and zero phase.

This should still permit usage of the current LLO setup for their fast ADC setup as well as any older DARM configuration scheme using the 65k ADC

Still to be worked out is whether there are additional delays on the sensing chain since there is no RCG transfer from the IOP model to USER model. The new setup has an IPC transfer to the 16k USER model. Still to be understood if this is going to cause some differences.