feat(gas): add tornado cash unshield + railgun unshield + transfer

[NicoSerranoP]

• Added railgun unshield + transfer benchmarks
• Added tornado cash unshield (there is no internal transfer available)
• Added privacy pools unshield (there is no internal transfer available)

[Copilot]

Pull request overview

This PR extends the gas benchmarking capabilities by adding unshield and transfer operation benchmarks for privacy-preserving protocols (Tornado Cash, Railgun, and Privacy Pools). The changes include a safeguard to prevent infinite RPC loops when insufficient historical events exist, and follow the established benchmarking patterns consistently across all three protocols.

Changes:

• Added MAX_NUMBER_OF_RPC_TRIES constant and retry limit logic in getEventLogs to prevent infinite loops when insufficient events are available
• Implemented benchmarkUnshield for Tornado Cash, Railgun, and Privacy Pools protocols
• Implemented benchmarkTransfer for Railgun protocol (internal private transfers)
• Added event ABIs and constants for unshield and transfer operations across all protocols
• Updated Tornado Cash Router documentation reference URL

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
gas-benchmarks/src/utils/rpc.ts	Added retry counter and MAX_NUMBER_OF_RPC_TRIES limit to prevent infinite RPC calls
gas-benchmarks/src/utils/constants.ts	Added MAX_NUMBER_OF_RPC_TRIES constant (set to 10)
gas-benchmarks/src/tornado-cash/index.ts	Added benchmarkUnshield method following established pattern
gas-benchmarks/src/tornado-cash/constants.ts	Added STAKE_BURNED_EVENT_ABI, TORNADO_CASH_RELAYER_REGISTRY, NUMBER_OF_UNSHIELD_EVENTS, and updated Router URL reference
gas-benchmarks/src/railgun/index.ts	Added benchmarkUnshield and benchmarkTransfer methods
gas-benchmarks/src/railgun/constants.ts	Added UNSHIELD_EVENT_ABI, NULLIFIED_EVENT_ABI, NUMBER_OF_UNSHIELD_EVENTS, and NUMBER_OF_TRANSFER_EVENTS
gas-benchmarks/src/privacy-pools/index.ts	Added benchmarkUnshield method
gas-benchmarks/src/privacy-pools/constants.ts	Added WITHDRAWAL_RELAYED_EVENT_ABI and NUMBER_OF_UNSHIELD_EVENTS

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[JohnGuilding]

Looks good!