[frontend] Add tweak for Merkle tree hashes

[paulcadman]

This PR adds a Keccak256 tweak circuit that will be used to hash the nodes in the XMSS merkle tree for the hash-based signature scheme.

[paulcadman]

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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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• [frontend] Add hash-based signature aggregation example #881
• [frontend] Add xmss multi-signature aggregation #880
• [frontend] Add xmss verifier #814
• [frontend] Add public key hash tweak #879
• [frontend] Add merkle tree verifier #813
• [frontend] Add tweak for Merkle tree hashes #812 👈 (View in Graphite)
• [frontend] Add Winternitz OTS verifier #811
• [frontend] Add message tweaking function #820
• [frontend] Add hash chain verification #808 : 2 other dependent PRs (#809 , #810 )
• [frontend] Make hash tweaking into a function #819
• main

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Merge activity

• Sep 1, 3:16 PM UTC: paulcadman added this pull request to the Graphite merge queue.
• Sep 1, 3:16 PM UTC: CI is running for this pull request on a draft pull request (#897) due to your merge queue CI optimization settings.
• Sep 1, 3:22 PM UTC: Merged by the Graphite merge queue via draft PR: #897.