- avoid making RPC request for `zero - zero` range
- avoid checking of nonce for a lower block in the range if it is zero
in a higher block
- on `wallet_getTransfersByAddress` scanning of history is skipped if
zero block is already reached
- no need to fetch block num before fetching token balances
If one request failed, the whole batch would fail.
This caused issue as one of the contract is constantly returning an
error now, and essentially there was not way to fetch balance.
Also extend the timeout to 20s as we throw 165 request to Infura in one
go and it takes its time to reply to those, although it seems like we
should batch them on our side instead of sending them all cuncurrently.