contracts: Implement rootClaim(uint256 l2ChainID) in SuperFaultDisputeGame.sol

[Inphi]

Implement the IDisputeGame.rootClaim(uint256 _l2ChainId) returns (Claim) interface in SuperFaultDisputeGame.sol. This requires that the SuperFautlDisputeGame can only be created with super root preimage. Note that the root claim, as super root, is still provided to the DG cwia (to serve as the game UUID). As a result, the SuperFaultDisputeGame must verify the super root preimage against the root claim. There's a helper function available to do this here.

Refer to https://www.notion.so/oplabs/Interop-Withdrawals-Using-Output-Roots-2bff153ee16280f19eebc55fa18b0212 for more details.

depends-on: https://github.com/ethereum-optimism/optimism/issues/18517