[fix] Error swaps to BNB accounts with memo flag set

Fixes #1818 (closed)

In bifrost if a memo "fails" to parse due to having a thorname affiliate (or other reason), and the swap/add destination is a valid BNB address, we should check that address for the bnb memo-flag. Previously we assumed the destination was a thorname, failed to resolve, and allowed the inbound to pass the filter.