fix: misc minor contract fixes

[LHerskind]

Fixing misc minor issues:

• The EIP-712 comment in TallySlashingProposer had wrong order of arguments
• The TallySlashingProposer had a explicit MUST be >0 in the comments but did not enforce it in the code
• Comment said 64 bits for a 32 bit value in FeeConfig
• Unused feeHeaders in the FeeLib, was not removed when we refactored the storage long ago
• Require the bond of the escape hatch to be > 0
• Remove the amount from the CandidateJoined since it was just a immutable value
• Remove the unsed proposerIndex and slot from the verifyAttestations
• Ensure that we do not get stale values from getVotes on the tally slashing proposer
• The getRound on the tally slashing proposer had a few unnecessary check that the _getRoundData was already doing.

[LHerskind]

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This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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• fix: misc minor contract fixes #20423 👈 (View in Graphite)
• fix: escape hatch snapshots #20363
• fix: fee related overflows #20362
• fix: skip empty epochs in tally slasher #20361
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