feat: Constrain chainid on L1 contract

[LHerskind]

Part of #824

The L1 state transitioner contract should constrain the chainid to always be equal that which is returned by block.chainid. The value is desirable to battle possilbe replay attacks if a version of the Aztec rollup exists on both Ethereum and another L1, but have the same "version" on both.

Should be included in the l2 block as well to make it clear where the block is expected to "hit".