Perform check of input format of timedata argument

[tnatt]

If the timedata argument is entered as a single list with one date e.g. timedata=["20240506"]
timedata_item will be a string in the function below and the unpacking is giving value="2" and label="0240506"

fmu-dataio/src/fmu/dataio/providers/objectdata/_base.py

Lines 211 to 217 in 7513f39

	def _get_fmu_time_object(self, timedata_item: list[str]) -> Timestamp:
	"""
	Returns a Timestamp from a timedata item on list
	format: ["20200101", "monitor"] where the first item is a date and
	the last item is an optional label
	"""
	value, *label = timedata_item

We need to either:

1. add check and provide descriptive error message to the user if the timedata argument is entered as a single list
2. add support for the single list format (which is a bit more intuitive than having to give it in as a double list). The double list could then only be used when a label needs to be attached to a date.

[tnatt]

Closed in #885