Track total minted on L2 native_bridge.move

[0xmovses]

Summary

The Informer needs to be able to know the total amount locked and minted across L1 and L2. For the L1 case this is fine as it just queries the NativeBridge.sol Move amount within the contract. For the L2 however, we do not track the total that is minted and burned on native_bridge.move.

Requirements

Create a global variable to track this value and write sufficient test coverage to check whether the value is indeed correct.