Token bridge portal contract (l2 native asset)

[LHerskind]

Includes:

• Noir contract for asset on L2 which supports:
  • Minting assets on L2
  • Transfers
  • Emitting an event to L1 for "withdrawals" and burn tokens
• Solidity contract for L1 asset which supports:
  • Minting assets by consuming a message from the message box

To test the solidity, we can simply fake the insertion of the message into the message boxes, e.g., fake the rollup.

The solidity relies on at least an interface for #516, and the noir side needs a way to emit the message #518