CSE: support aliases for contract fields

[palinatolmach]

We should add NatSpec annotations that allow to indicate that contract fields correspond to the same contract/account, e.g. /// @custom-kontrol-alias: escrowOne.oneEth, escrowTwo.oneEth,. They could then be used when CSEing contracts such as Governance:

contract Governance {
   OneEth oneEth;
   EscrowOne escrowOne;
   EscrowTwo escrowTwo;
   ...
}

contract EscrowOne {
   OneEth oneEth;
   ...
}

contract EscrowTwo {
   OneEth oneEth;
   ...
}

in order to only generate a single account for oneEth instead of three (one for each contract involved).