Audit changes

[sbauch]

Implements recommended changes. Generally we are adding more data to the OffchainError lookup and signing all of that data on this API. The contract then has more confidence between the verifications it performs.

• handles new shape of callData param from OffchainLookup error
• uses chain ID values from callData to be more chain agnostic - ENV no longer needs to specify RPC URLs, just an Infura key, meaning we dont need separate instances for testnets
• will not sign bundle if provided nonce does not match contract state nonce for the signer address