feat(core,chain): implement Display, FromStr, FromSql and ToSql for BlockId

[luisschwab]

This PR implements Display, FromStr for BlockId, and FromSql and ToSql for Impl<BlockId>, needed to persist the wallet's birthday as a BlockId (height + hash).

Changelog notice

• Implement Display and FromStr for BlockId
• Implement FromSql and ToSql for Impl<BlockId>

[evanlinjin]

ntACK fd9d558

[oleonardolima]

Concept ACK

It looks good, though I want to test it with the bdk_wallet companion PR before fully ACK'ing it.

[oleonardolima]

Also, the PR description is missing the CHANGELOG info.

[oleonardolima]

@luisschwab If you are looking forward to have this on 0.23.3 you'd need to either change the target branch to release/chain-0.23.x or open another backport PR alongside this one.

[luisschwab]

@oleonardolima I'll make a backport PR once this is merged on master.

[ValuedMammal]

It's not obvious that BlockId would have a FromStr impl, or that it would be implemented this way. I assume you can always persist a BlockId as two separate columns for the height and block hash.

[luisschwab]

It's not obvious that BlockId would have a FromStr impl, or that it would be implemented this way. I assume you can always persist a BlockId as two separate columns for the height and block hash.

Do you think that's a better approach? I think this is a pretty sane and straight forward way to persist it.