* Add plugin option for protogen in Makefile
* Fix the generator for the plugin in util/protogen
* Erase convertable types, move helpful methods to gRPC protobufs
* Erase helpers for convertations
* Generate StableMarshlal/StableSize for protobufs by the protoc plugin
Signed-off-by: Airat Arifullin a.arifullin@yadro.com
Define `subnet.Info` structure of corresponding message from NeoFS API
protocol. Provide field getters and setters. Implement
`StableMarshal` / `StableSize` methods of binary encoding. Implement
`ToGRPCMessage` / `FromGRPCMessage` method for testing and
potential transport.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>