Add safe way to update last seen arbitrarily

[matthiasdebernardini]

If you go in and change the last seen update on the database, then it breaks the application

[matthiasdebernardini]

Lets say you make a wallet;
then generate an address
then deposit coins to that address
then generate a new address but you hold onto it and do nothing with it

then you want to resync your wallet
so you import over the descriptors and resync with electrum you only get your last seen to 1 (not 2 as it previously was)

if you then log into your postgres instance and manually change that last seen value (for the external keychain) to 2 it breaks the application with no warning or errors either from sqlx or from bdk

what I think is happening @notmandatory help me out here if I am off base

but if you manually change the last seen field, then it looks for corresponding block height updates?

in any case, it should be noted in the readme not to manually update that data and instaed use a safe method provided by the library

[notmandatory]

Do you have any stack info on where it panics? It's always a good idea to use the APIs and not try to change data in the tables anyway since, as in this case, there's usually more going on than just reading the data.

I suspect we're keeping track of the last seen in multiple places and panic if they don't match.