Add Adaptive Multitaper Method feature to PySPEDAS

[jameswilburlewis]

Hector Salinas has produced a Python implementation of the Adaptive MultiTaper periodiciticy detector that Simone di Matteo has contributed to IDL SPEDAS. We should add an interface to his package to PySPEDAS.

https://pypi.org/project/amtm-signaldetect/

It's still under active development, but perhaps the interface is stable enough at this point to write a wrapper.