Update InterMine data source API to use fields as parameters instead of types

[alancleary]

Some of the InterMine data source API functions take objects as parameters and then extract the field values they need from the objects. These objects are actually defined by the InterMine data source and are intended for internal use only. As such, using these objects as API parameters reveals implementation details and forces resolvers to coerce input values into an arbitrary object. For this reason, all InterMine data source API functions that use these object parameters should be updated to use individual fields instead.