[api] v2alpha1: Malfeasance API

[kacpersaw]

Description

Currently, API for malfeasance is only present in V1. The ask is to create v2alpha1 malfeasance service for list and stream.

message MalfeasanceProof {
    SmesherId smesher_id = 1;
    LayerNumber layer = 2;
    enum MalfeasanceType {
        MALFEASANCE_UNSPECIFIED = 0;
        MALFEASANCE_ATX = 1;
        MALFEASANCE_BALLOT = 2;
        MALFEASANCE_HARE = 3;
    }
    MalfeasanceType kind = 3;
    string debug_info = 4;
    bytes proof = 5;
}