New Withdrawal API Field - on_chain

Platforms can now query our API and be aware that a crypto withdrawal has been confirmed on-chain.
The field is called on_chain_status and its possible values are
- PENDING: The withdrawal has been broadcasted on-chain but is not yet confirmed
- CONFIRMED: The withdrawal has been sufficiently confirmed on-chain according to our confirmation thresholds, which can be viewed here in Confirms column here.
Full 1-pager on how to interpret the GET /withdrawals/requests and GET /withdrawals/requests/:id response found here.