Add time units and calendar to data catalog

[bouweandela]

These are needed to select the parent experiment:

climate-ref/packages/climate-ref-esmvaltool/src/climate_ref_esmvaltool/recipe.py

Lines 265 to 280 in 5c0817f

	with (
	xr.open_dataset(parent_path, decode_times=time_coder) as parent_ds,
	xr.open_dataset(child_path, decode_times=time_coder) as child_ds,
	):
	branch_time_in_parent = cftime.num2date(
	child_ds.attrs["branch_time_in_parent"],
	units=parent_ds.time.encoding["units"],
	calendar=parent_ds.time.encoding.get("calendar", "standard"),
	)
	branch_time_in_child = cftime.num2date(
	child_ds.attrs["branch_time_in_child"],
	units=child_ds.time.encoding["units"],
	calendar=child_ds.time.encoding.get("calendar", "standard"),
	)
	child_start = child_ds.time.values[0]
	parent_start = branch_time_in_parent - branch_time_in_child + child_start