* 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
`expiration_epoch` field of `StorageGroup` message has been marked as
deprecated in previous NeoFS API protocol's release.
Mark all method related to the field as deprecated. Leave and use them
for test purposes only.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>