Cavity pole frequency uncertainty fix

Historically, the uncertainty budget did not include any cavity pole frequency from the MCMC, only the TDCF value uncertainty. This MR now calculates the sampled cavity pole frequency so that it includes the uncertainty from both MCMC and TDCF contributions.

The sample_response() method creates response function curves by sampling the MCMC and TDCF values for sensing and actuation function parameters. The nominal_response() method creates a response function curve assuming the mean MCMC and mean TDCF values are creating the nominal response.

Closes #59 (closed)