Add Params gRPC to transfer

[colin-axner]

Summary

Add a Params gRPC for the ics20 module. Following #2010 we will need to self manage our own params. Thus it makes sense to expose a Params gRPC as soon as possible for backwards compatibility purposes

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[colin-axner]

We should backport (minor release) to any versions for which we will still be supporting when the x/params module is deprecated

[crodriguezvega]

If I'm not mistaken, this is actually already implemented:

• rpc service definition in proto/ibc/applications/transfer/v1/query.proto.
• implementation of gRPC endpoint in modules/apps/transfer/keeper/grpc_query.go with corresponding tests.
• CLI query in modules/apps/transfer/client/cli/query.go.

[colin-axner]

Yup! Looks like it to me