In the case that `decrypt_and_store_transaction` is being used to add
data for fully-transparent transactions to the database, it may be the
case that there is no existing relationship between a transaction and
the block height at which it was mined (unlike for transactions being
enhanced after discovery via block scanning.) This change makes it
possible to set the mined height for transactions that do not have any
shielded components that involve the wallet.
This implements a priority queue backed by the wallet database for scan
range ordering. The scan queue is updated on each call to `put_blocks`
or to `update_chain_tip`.
Jack Grigg
Kris Nuttycombe
Kris Nuttycombe
zancas