Add support for attributes to add_entities

[mdekstrand]

Right now, add_entities only takes entity IDs. A data frame or Arrow table with other entity attributes is rejected, and clients need to use the various add_???_attribute methods.

I always intended for us to be able to include attributes in add_entities, when called with a DataFrame or Table.

This issue is to add support for that, to make it easier to add a data frame of entities with attributes.