Essreduce + Essimaging + Essnmx: tofectomy

[nvaytet]

Replacing time-of-flight with wavelength in the GenericTofWorkflow, which is now called GenericUnwrapWorkflow.

Note: once this is merged, every package using the GenericTofWorkflow not in the monorepo will break...

[jokasimr]

I'd prefer that we keep the WavelengthInterpolator but when calling the InterpolatorImpl we pass lookup.data.values * self._distance_edges and in WavelengthInterpolator.__call__ we return
values=self._interpolator(...) / ltotal (but making that operation in-place is probably better).

Then I don't think we have to make other changes elsewhere or re-introduce tof, right?

[nvaytet]

Yes, I thought about it some more, and basically did just what you suggest here.

[nvaytet]

@YooSunYoung can you take a look to make sure I didn't mess up anything in essnmx?

[nvaytet]

A final thought (in the context of breaking changes):

Do we want to make it compatible with old lookup tables that stored tof instead of wavelength?
Basically load the table, look at the units. If they are time units, convert to wavelength on the fly?
Meaning that we don't necessarily need to update all lookup tables in our databases?

But it may make things confusing that the files are still called something with tof_lookup_table?

[nvaytet]

We leave this out for now. Time of arrival should instead be computed from event_time_zero and event_time_offset (see scipp/scippneutron#685)

[nvaytet]

This should be computed from event_time_zero + event_time_offset using Scippneutron instead: scipp/scippneutron#685

This was computing some strange unwrapped arrival time offset, but it cannot be used to trace back what the time was at sample. The name is confusing, so we remove it for now (it wasn't used by anything so far).

[YooSunYoung]

It seems fine with NMX...!

[jokasimr]

A final thought (in the context of breaking changes):
Do we want to make it compatible with old lookup tables that stored tof instead of wavelength?
Basically load the table, look at the units. If they are time units, convert to wavelength on the fly?
Meaning that we don't necessarily need to update all lookup tables in our databases?

It would be nicer to have a clean break without adding the complexity of having a fallback for old tables, if we can get away with it, and I think we can.
Old tables can still be used by not upgrading the packages to the latest version.