Storing tokenized single cells

[nleroy917]

It would be nice to be able to store individual, tokenized cells so that we can share tokenized datasets that are used for training machine learning models.

The data might look like this:

cell1 = [999, 101, 22]
cell2 = [123, 456, 89, 99999]
cell3 = [1]

These are all tokenized to one universe, but there's really no "bed file" that is to be "tokenized"... so this needs to be addressed. From discord. AKA -- "unlinked tokenized bedset"

unlinked: because the individual bed files don't actually exist as entities in bedbase.
tokenized: because they're all defined in terms of a universe
bedset: because it's many of them (like, 100,000 of them). -- also why each one is not its own entity in the db.