Accuser: denounce consensus operation with different slots

Context

This MR fixes https://gitlab.com/tezos/tezos/-/issues/5094. The accuser now denounces consensus operation with different slots for the same level and round.

This MR sits on top of !7927 (merged) which allow consensus operations with non-minimal slot in the mempool.

It also depends on !8099 (merged) which makes the accuser await for the protocol to start. Therefore, the constants fetching present in this MR will not fail.

Manually testing the MR

CI green, more tests will follow in !8085 (merged)

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR