MAINT: rename query_target methods to query_object be consistent with the rest of the API

[bsipocz]

I've noticed the API inconsistency in esa.hubble and esa.jwst to use the name query_target as opposed to what we do in the rest of the package.

I suppose we could rename (with appropriately long deprecation for the old names) to make the API more consistent.

cc @jespinosaar