Implement GFIX preprocessing

[alejoe91]

From https://billkarsh.github.io/SpikeGLX/help/catgt_tshift/catgt_tshift/:

"-gfix=0.40,0.10,0.02. This requires that a transient artifact must attain a peak amplitude of at least ||0.40 mV||, must reach its peak as least as rapidly as ||0.1mV/sample-tick||, and the transient is over when the amplitude settles back to ||0.02 mV|| or smaller"

[WeissShahaf]

any news on implementing GFIX?
it's a great tool and the only thing missing for switching from catGT functionality in spikeinterface

[alejoe91]

@WeissShahaf we are holgin a hackahton at th end of the month. I'll put this in as a project ;)

[alejoe91]

SpikeInterface/SpikeInterface-Hackathon-Edinburgh-May24#39