epic: Relayer Transaction Monitoring Service

[Eikix]

Describe the enhancement request

Kakarot just landed on Starknet Sepolia, making the network EVM compatible. EVM Transactions are relayed by a permissionless fleet of relayers operated currently by Kakarot Labs.

There is currently no visibility / observability framework to compute statistics on the transactions that are being emitted by relayers. We need a service that's able to:

• Link an EVM transaction hash with its corresponding Starknet Transaction Hash for ease of debug
• Alert Kakarot Labs if relayer transactions are being rejected
• Receive/Index receipts of relayers transactions and alert if transactions are being reverted -> Why? Because transactions MUST not be Starknet reverted (if they revert in EVM world, they are still successful but carry a failure flag)

Describe Preferred Solution

• A Relayer Transaction Monitoring Service - needs further scoping by @greged93 and @tcoratger

Tasks

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1. Link Ethereum and Starknet transactions hashes so that Kakarot Labs team member can easily pick up an Eth transaction hash from a user and gather information on the transaction
2. Be able to alert Kakarot Labs if OZ relayer service faces "transaction rejected" on Starknet, and give us the reason
3. Be able to draw statistics on % of Successful relayer transactions on testnet (note that for relayers, starknet reverted transactions are not reimbursed)
4. Be able to alert if transactions are being Starknet reverted

[Eikix]

Needs scoping with respect to technical strat cc'ing @ClementWalter