kv,server: implement error serialization support in gRPC

[irfansharif]

We currently have code in CRDB that looks like the following:

cockroach/pkg/cli/error.go

Lines 356 to 364 in 9ba4404

	// Are we trying to re-initialize an initialized cluster?
	if strings.Contains(err.Error(), server.ErrClusterInitialized.Error()) {
	// We really want to use errors.Is() here but this would require
	// error serialization support in gRPC.
	// This is not yet performed in CockroachDB even though the error
	// library now has infrastructure to do so, see:
	// https://github.com/cockroachdb/errors/pull/14
	return server.ErrClusterInitialized
	}

We're essentially string matching on the specific error and using that in our control flow; it makes for fragile code. As of cockroachdb/errors#14, our errors package now has the infrastructure to support error serialization in gRPC. It'd be nice to implement it and start promoting this errors.Is(...) usage pattern across RPC boundaries, in the same way we do for "local" errors.

Jira issue: CRDB-2971

[ajwerner]

Is there anything blocking this? This would be great!

[irfansharif]

+cc @erikgrinaker.