Get metadata by file id on EOS GRPC

[labkode]

Add to https://github.com/cs3org/reva/blob/master/pkg/eosclientgrpc/eos_grpc/eos_grpc.proto#L165
a method to get information by file id as done in:
#1079

[ffurano]

I can add it to the proto, yet It will also have to be added to the EOS MGM

[labkode]

@ffurano please do send a PR to: https://github.com/cern-eos/grpc-proto

[ffurano]

The protocol (and likely also the MGM server itself) supports getting metadata by fileid.
It's sufficient that the client app properly fills the data structure message
MDId {
bytes path = 1;
fixed64 id = 2;
fixed64 ino = 3;
TYPE type = 4;
}
which is part of the query.