Clean up SmesherID

[lrettig]

We have contradictory types for smesherID:

api/proto/spacemesh/v1/smesher_types.proto

Lines 52 to 54 in 9474f58

	message SmesherIDResponse {
	AccountId account_id = 1;
	}

and

api/proto/spacemesh/v1/types.proto

Lines 30 to 32 in 57864fb

	message SmesherId {
	bytes id = 1;
	}

Unify these. Should the ID be bytes or AccountId?

Note that we define SmesherID in go-spacemesh to be a NodeID: https://github.com/spacemeshos/go-spacemesh/blob/d4c11da68a0521ec8e23da1f3fd4a4a25c32de94/activation/activation.go#L76

which gets turned into an address: https://github.com/spacemeshos/go-spacemesh/blob/d4c11da68a0521ec8e23da1f3fd4a4a25c32de94/api/grpcserver/smesher_service.go#L114