Enable provider to verify lunatic attacks on consumers

[mpoke]

Summary

The cryptographic equivocation feature doesn't take lunatic attacks into consideration.

Problem Definition

Currently, the provider can verify evidence of light client attacks on the consumers only for equivocation as lunatic attacks would require access to all the previous headers.

Proposal

A suggestion is to take advantage of epochs and come up with an algorithm that enables the provider to verify evidence of lunatic attacks on the consumer.

Task list

Must have

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1. discuss proposal (if proposal rejected, close EPIC)
2. create ADR (if ADR rejected, close EPIC)
3. add sub-tasks needed to implement the proposed feature

Nice to have

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1. add sub-tasks that are nice to have for the proposed feature