Support abi encoding of EVM tuple types

[sisyphusSmiling]

Problem Definition

Currently, it's not possible to encode calldata from cadence for an EVM tuples. Tuples are often used to encode custom structs defined in solidity contracts. For example

// given some struct S
struct S {
  uint8 x
  uint32 y
}

// and some function foo which takes S as a parameter
function foo(S s) public view returns (uint8) {
  return s.x
}

The function signature would be foo((uint8,uint32)) which is not encodable using existing EVM abi encoding API. Current workarounds require anyone integrating with such a contract to deploy a Solidity proxy/shim accepting the tuple's unpacked args which calls through to the final contract as workaround, increasing developer friction. Unfortunately, this is a common pattern in Uniswap's more recent contracts (example reference).

Proposed Solution

At a high level, support abi encoding tuples which would indirectly support encoding custom structs. I'm not certain this is trivial due to the lack of a tuple type in Cadence.

Definition of Done

Developers can successfully encode tuple calldata and make calls to Solidity functions which accept tuples (and secondarily custom structs) as parameters.