User may need some time to open their wallet to approve signature
request and miss it.
If we have a active request, re-send it if we see a
wallet_ready signal, suggesting the wallet was just opened.
This backward compatible change allows wallets/dapps to add additional
features outside the basic transaction signature support to the
hdwalletv1 protocol.
This solves an issue where wallet has to scan address ranges for each
derivation path and match it to locking script to figure out what
private key to use for signature.
This is a waste of effort and unnecessary complex for wallet
implementations since the dapp side already knows what inputs its using.
