report_equivocation: TxDescriptor<{
    equivocation_proof: {
        equivocation: GrandpaEquivocation;
        set_id: bigint;
    };
    key_owner_proof: {
        session: number;
        trie_nodes: Binary;
        validator_count: number;
    };
}>

Report voter equivocation/misbehavior. This method will verify the equivocation proof and validate the given key ownership proof against the extracted offender. If both are valid, the offence will be reported.