Feature request: track disputes for valdiators

[tugytur]

It would be nice to also monitor if a validator is causing disputes.

Disputes happen if a validators becomes a p/v and submits invalid blocks and this is concluded by 2/3 of the validators.
This can be caused by a bug, hardware issues, corrupt DB and so on.

Most of the time if disputes happen some kind of action is required from the validator operator.
Since December there were multiple instances where a disputes by one validator affected the relay chain badly.

Disputes can be tracked with the module: ParaDisputes, event: DisputeConcluded

Thanks