Move serdes deserialization out of DagsterGrpcClient
Summary: Doing this in the callsite instead gives us more flexibility with back-compat, since we might just want to pass through the results of a gRPC client in some contexts without deserializing it.
Test Plan: BK
Reviewers: alangenfeld, max, johann
Reviewed By: max
Differential Revision: https://dagster.phacility.com/D8940