Add Units to Metadata

[Rodot-]

Is your feature request related to a problem? Please describe.

Describe the solution you'd like
Add units to the metadata of the carsus atomic data corresponding to each dataframe. Will require update to minor version info.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[andrewfullard]

Or: make sure everything is converted to the same units, probably a better general way to avoid parsing concerns. Currently done, but unclear what the units are