Standardize Neuropixels Probes values

[bparks13]

ProbeInterface has added the IMEC probes to their library of probes, where they now define the (0,0) coordinate as the location of the first electrode (see here, for example). Now that these probes exist in their probeinterface_library repo, it would probably be best for us to match those values instead of generating our own internally for the Onix1 library.

We should discuss the best way to do this, but one way would be to add the probeinterface_library repo as a submodule to this repo, and instead of generating the ProbeGroup directly (i.e., like this), we could utilize the existing LoadExternalProbeInterfaceFile and point it to the ProbeInterface file from the submodule.