Change ComputeSpikeLocations to use only peak_sign

[ecobost]

Fixes #4320.

Instead of receiving spike_retriever_kwargs (which was not used anyway), receive peak_sign (mirroring ComputeSpikeAmplitudes). Previous default behavior and capabilities will not change (as peak_sign was the only parameter actually used from spike_retriever_kwargs).

Code will change from

analyzer.compute('spike_locations', spike_retriver_kwargs={'peak_sign': 'both'}) # previous version
analyzer.compute('spike_locations', peak_sign='both') # new version

[ecobost]

Forgot to change references to spike_retriever_kwargs in other code/docs/test.

I found there is only one place where it was used:

spikeinterface/src/spikeinterface/benchmark/benchmark_peak_localization.py

Lines 27 to 30 in 5b2e738

	if not self.channel_from_template:
	self.params["spike_retriver_kwargs"] = {"channel_from_template": False}
	else:
	## TODO

As said in #4320, this didn't actually have any effect (cause spike_retriever_kwargs was not passed to SpikeRetriever()), so I commented this code out.I think spike_locations.py is cleaner/easier-to-understand receiving only peak_sign as argument but if you think the use case in benchmark_peak_localization.py warrants the extra complexity, let me know and I'll revert the changes (and make sure spike_retriever_kwargs is forwarded to the SpikeRetriever).