add data_description field to flag non-AIND data

[tmchartrand]

This is primarily useful to make explicit the exception that we only require the data description metadata for such assets (while for AIND data we require either processing or subject etc)

[tmchartrand]

Saskia and I discussed one possibility would be to add a new data_level for this, which we are tentatively calling "non-registry" data. @dbirman thoughts?

[dbirman]

Saskia and I discussed one possibility would be to add a new data_level for this, which we are tentatively calling "non-registry" data. @dbirman thoughts?

Is this for intermediate results or for external data where we don't have additional information? I think either way "non-registry" doesn't quite make sense to me...

[tmchartrand]

this is for external data where we don't have additional information. terminology is one question ("non-AIND" or "external" are other options but both have flaws), what I was trying to get at for now is whether adding the concept to data level seems reasonable at least?

[dbirman]

Our original definition for data level was "Level of processing asset has undergone" so this seems very different from that. I think we just need to add a new field for this and rework the file requirement system around that. I already don't like how we snuck in skipping instrument metadata for external assets...