Support Qxy in run mapping

[SimonHeybrock]

Currently we are only applying map/reduce for WavelengthScaledQ:

esssans/src/ess/sans/workflow.py

Lines 96 to 107 in 20e3807

	def _set_runs(
	pipeline: sciline.Pipeline, runs: Iterable[str], key: Hashable, axis_name: str
	) -> sciline.Pipeline:
	pipeline = pipeline.copy()
	runs = pd.DataFrame({Filename[key]: runs}).rename_axis(axis_name)
	for part in (Numerator, Denominator):
	pipeline[WavelengthScaledQ[key, part]] = (
	pipeline[WavelengthScaledQ[key, part]]
	.map(runs)
	.reduce(index=axis_name, func=merge_contributions)
	)
	return pipeline

This should be extended to also apply the equivalent to the WavelengthScaledQxy branch of the graph.