feat: getNonce and setNonce cheatcodes

[mds1]

interface Vm {
  // Gets the nonce required for the next transaction
  function getNonce(address) external;
  // Sets the next required nonce, where new nonce must be > current nonce
  function setNonce(address,uint256) external;
}

Use cases:

• Precompute addresses that should be emitted from logs in factory contracts, e.g. getting values of emitted events #543
• Asserting an addresses nonce is what you'd expect, to facilitate deterministic deploys in feat(forge): Better deployment #402