CCIP Read support for transactions

[gskril]

Viem already has native support for CCIP Read in a read context (which is awesome), but technically the spec is also meant to work with transactions. See https://eips.ethereum.org/EIPS/eip-3668#use-of-ccip-read-for-transactions

See https://github.com/gskril/solidity-fetcher for an example use case.

General flow:

• User initiates a transaction awaitFoo() that reverts with the standard CCIP Read error
  • OffchainLookup(sender, urls[], calldata, callbackFunction, extraData)
• Viem decodes the error and makes the relevant HTTP call according to ERC-3668
  • const res = fetch("https://example.com/{sender}/{calldata}")
• Viem initiates a transaction with the response from the HTTP call and the original request to the specified callback function from step 1
  • foo(bytes memory res, bytes memory extraData)

Note the security consideration from the ERC:

Client libraries should disable CCIP read for transactions (but not for calls) by default, and require the caller to explicitly enable this functionality. Enablement should be possible both on a per-contract, per-domain, or global basis.

I'm trying to figure out a way to get similar behavior without an upstream integration, but I haven't come up with a clean solution yet.