Stop adding units to emitted data keys

[U8NWXD]

Currently, when we emit data that has a unit in the state hierarchy and format it as a timeseries, we put the unit into the key and strip the units from the value. For example, we might get:

{
    'external': {
        ('antibiotic', 'millimolar'): [1, 2, 3],
    }
}

This is not ideal. Instead, our plotting functions should know how to handle Quantity objects.

Here's where we do the unit conversion:

vivarium-core/vivarium/library/dict_utils.py

Lines 264 to 268 in 6836411

	if isinstance(value, Quantity):
	unit_key = (key, str(value.units))
	if unit_key not in timeseries:
	timeseries[unit_key] = []
	timeseries[unit_key].append(value.magnitude)

And here's a trace of the calls in emitter.py that lead to the code above:

• vivarium.library.dict_utils.value_in_embedded_dict()
• vivarium.core.emitter.timeseries_from_data()
• vivarium.core.emitter.Emitter.get_timeseries()

Note that addressing this will probably be a breaking API change since doing so will change our output format.