Add Query (no stream) handler in Wasm Query Service

[jubeless]

The current WASM query implementation registers all services as streams

substreams-sink-kv/server/wasm/server.go

Lines 32 to 42 in 622a3eb

	for _, methodConfig := range config.Methods {
	handler, err := wasmEngine.GetHandler(methodConfig, protoCodec, logger)
	if err != nil {
	return nil, fmt.Errorf("failed to get handler: %w", err)
	}
	grpcService.Streams = append(grpcService.Streams, grpc.StreamDesc{
	StreamName: methodConfig.Name,
	Handler: handler.handle,
	ServerStreams: true,
	})
	}

Irrelevant of the proto specification

substreams-sink-kv/server/wasm/testdata/wasmquery/test.proto

Lines 7 to 12 in 622a3eb

	service TestService {
	rpc TestGet(GetTestRequest) returns (stream Tuple);
	rpc TestGetMany(TestGetManyRequest) returns (stream Tuples);
	rpc TestPrefix(TestPrefixRequest) returns (stream Tuples);
	rpc TestScan(TestScanRequest) returns (stream Tuples);
	}

There is no point in supporting stream since our current WASM query handler returns a single message. We should either support both or migrate everything to a single message request response.

[jubeless]

Close with commit 9fdb804