In this commit, we add a migration that will be used by existing wallets
to ensure they can adhere to the new requirement of storing up to
MaxReorgDepth entries within the block hash index.
In this commit, we modify the dropwtxmgr tool to force a rescan upon
restart from the wallet's birthday block, rather than the chain's
genesis block. We can safely do this as we expect that no on-chain
events relevant to the wallet should happen before this block. For
older wallets which do not have their birthday block set, the rescan
should start from the genesis block.
In this commit, we add a migration to force a rescan of users' wallets
starting from their birthday block to ensure that their balance is
reflected correctly as it is on-chain. This was inspired by the recent
bug discovered where the wallet would not watch for the confirmation of
a relevant transaction.
In this commit, we add a new migration to the waddrmgr to populate the
birthday block for existing wallets. This will deem useful when
performing rescans for whatever reason, as we'll now be able to start
from this point rather than the genesis block, incurring a longer
rescan.
The migration is not as reliable since we do not store block timestamps,
so we'll need to estimate our height by looking at the genesis timestamp
and assuming a block occurs every 10 minutes. This can be unsafe, and
cause us to actually miss on-chain events, so a sanity check will be
added before the wallet attempts to sync itself in a later commit.
