Remove the header store

[rustaceanrob]

Given bitcoindevkit/bdk#1582, it seems as BDK will eventually be able to accept both Header and BlockHash to the LocalChain. If it is assumed the underlying wallet will have block headers, not just hashes, then there is an opportunity to remove data redundancy.

A future flow would look like:
User supplies a recent history of the headers they know about -> The node starts with this history, informing the user of any reorgs -> The node emits the last N headers the user cares about -> The user stores these headers for the next sync

Before this goes in for certain, we will need to confirm that block headers can be stored/fetched from BDK sqlite. Users of the library that do not use BDK will have to keep their own snapshots, but this is a great opportunity to reduce the maintenance scope. Pros outweigh the cons IMO

[thunderbiscuit]

Can I ask where these headers will be stored moving forward? I took a quick glance at the code diff but didn't see anything that jumped at me. I assume this is now the user's responsibility somehow?

Just trying to make sure I'm staying on top of the big architectural changes coming down the pipe for Kyoto, at least in my rough mental model of things!

[rustaceanrob]

I was working on a description as you commented! @thunderbiscuit

[rustaceanrob]

While you're hanging out in this part of town, do you have an opinion on #445 @thunderbiscuit?

[thunderbiscuit]

Cool! I commented there. 👍