Rewrite client code without use of any

[tstirrat15]

Related to #170. The types were wrong around importBulkRelationships because the client has a lot of implicit behavior and overrides types using any.

This could also probably be done in the context of #179.

This would likely be a breaking change, because I'm not sure how to retain the implicit behavior while also writing things in a statically analyzable fashion. I think it'd be more likely that we just expose the nice-grpc client rather directly.