Polling fall back for Swift order confirmation

[tmns]

It's been reported that order confirmation logic is taking longer than it should to initiate. After some debugging, looks like it's specific to Swift orders, and arises from the confirmed event lagging to fire.

Currently we use an initial fetch & WS to watch for the order confirmation and relay the confirmed event. I think it's possible that sometimes something like the following happens:

1. Initial RPC fetch runs immediately. At this point, possible that the order has not been confirmed yet (i.e. too early).
2. WS sub waits for account changes.
3. WS fails/misses the event for some reason.
4. Final RPC fetch after the full timeout.

This PR in turn adds polling in addition to the WS sub, so that in case something like the above happens, we can pick up the event without waiting for the full timeout.