Fix rxFrequencies

[jusack]

Closes #105, maybe fixes #101

I changed some functions in Derived.jl to use FFTW or built-in julia functions and added tests, which would have caught issue #105

[tknopp]

yes, using rfftfreq is definitely better.

[jusack]

The first test fail was Aqua finding am ambiguity between Base and Interpolations, I bumped the Aqua compat where the default behaviour is now to only look at the tested package.
However, now the test on the UniformRandomPositions fails on Julia 1.11 (and not on 1.10). I opened an issue on that (#108)

[nHackel]

I think we also need to adapt the frequency calculations in the frequency filters to stay consistent. For example minFreq -> minFreqIdx should be the same as the one from rxFrequencies.

To reuse rfftfreq here we would need to find the first frequency that is the same or larger/smaller depending on min or max freq and use that index. We can use functions like searchsortedfirst to exploit the fact that our frequencies are sorted