Add check `fee==0` in deposit to near

[olga24912]

Currently, when we deposit to near the Eth we ignore the fee argument (https://github.com/aurora-is-near/aurora-eth-connector/blob/master/eth-connector/src/lib.rs#L563)

So, we should add the extra check that fee == 0 and add comment that it is deprecated argument. https://github.com/aurora-is-near/eth-connector/blob/master/eth-custodian/contracts/EthCustodian.sol#L88

More details: Near-One/aurora-eth-connector#29