feat(analysis.flagging.IterHPFMask): Task to generate frequency mask …

[tristpinsm]

…using iterative HPF.

I've translated the code I was using to generate frequency masks from ringmaps using the iterative HPF method that Seth developed to identify narrow-band-gain features. I've made the task such that it should work on other containers/datasets/axes, but more experimentation would be required to figure out where it could be useful.

[tristpinsm]

here's a plot that shows the RMS of a high-pass filtered map with and without the iterative mask applied

in this case the masking is not very aggressive but it brings down the residuals a fair bit

And here's a randomly selected frequency that is pretty typical