Time disputes

[kamilsa]

paritytech/polkadot-sdk#742 introduces the timed disputes. We should support them as well.

New objectives:

• Allow for very long approval voting timeouts.
• Discourage malicious actors from trying to delay the voting process.
• Give approval checkers an incentive to actually do the validation.

Proposed changes:

• Charge backers for excess time proportional to the amount.
• Slash backers on concluding invalid disputes, but also other nodes voting valid if the timing reported by approval checkers is low enough.

Benefits:

• A more robust and less vulnerable approval voting process.

[eskimor]

Slash backers on concluding invalid disputes, but also other nodes voting valid if the timing reported by approval checkers is low enough.

I think this should be "high enough". If the network (via a dispute and the median) finds the time to execute a candidate to be higher than the backing timeout, we can assume backers have been dishonest and can slash them - together with other nodes voting such low values.

Anyhow, with our new disabling strategy, time disputes are less critical and we de-prioritized them as of now. (Not likely to land 2024, assuming nobody raises a significant concern.)

[kamilsa]

@eskimor thanks for your comment! Unfortunately, the link to disabling strategy is not clickable