Implement Multitaper spectral analysis method

[Clément Le Couedic]

Multitaper spectral analysis provides a more accurate information than Welsh periodogram:
high frequency resolution and low variance
https://raphaelvallat.com/bandpower.html

MNE library already provides a python implementation for this algorithm
https://martinos.org/mne/dev/generated/mne.time_frequency.psd_multitaper.html