feat: contract_call event capture

[ctoyan]

Description

After https://github.com/eigerco/giza-axelar-starknet/issues/77 and https://github.com/eigerco/giza-axelar-starknet/issues/78, we need to capture the ContractCall event from Starknet, in order to prepare it for verification against the Axelar message passed from the relayer.

Requirements

• Add ampd boilerplate for starknet as a new chain
• Intercept the ContractCall message
• Prepare it for verification agains the Axelar message

Todos

• Unit tests
• Manual tests
• Documentation
• Connect epics/issues

Steps to test manually

• Run a starkli command to execute call_contract on the gateway, so it can emit a ContractCall event.
  For example -
  starkli invoke 0x055fddb9d939ab8c6cfd5a9871663457cd5b2fcb9dad9cdf464a12f1e045c4d4 call_contract str:destination_chain 4 0x4c6f6e67206c6f6e6720737472696e672c2061206c6f74206d6f72652074 0x68616e2033312063686172616374657273207468617420776f756c646e27 0x74206576656e2066697420696e2074776f2066656c74732c20736f207765 0x276c6c2068617665206174206c656173742074776f2066656c747320616e 0x6420612070656e64696e6720776f72642e 17 5 104 101 108 108 111, which equals the following event ContractCallEvent { destination_address: "Long long string, a lot more than 31 characters that wouldn't even fit in two felts, so we'll have at least two felts and a pending word.", destination_chain: "destination_chain", source_address: "0x00b3ff441a68610b30fd5e2abbf3a1548eb6ba6f3559f2862bf2dc757e5828ca", payload_hash: 0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8 }
• Construct a message corresponding to the one above and send it to axelar verifier
• Check if the message has been verified in the verifier contract