Scan verified blocks from sapling activation to the tip

[teor2345]

Motivation

We want to scan all the blocks in the state, this is the ticket for scanning verified blocks from sapling activation to the tip.

Suggested Design

Count from sapling activation height to LatestChainTip.best_tip_height(), ask the state for each block, then scan it. If there is no block for a height, wait 10 seconds, then try that height again in a loop.

Outside the state there is no distinction between finalised and non-finalised blocks, so this design will scan all of them.

Out of Scope

• feat(zebra-scan): Immediately scan newly verified blocks #7905

[mpguerra]

Hey team! Please add your planning poker estimate with Zenhub @arya2 @oxarbitrage @teor2345 @upbqdn

[arya2]

I blocked closing this on #7947, but most of the changes can be made without it.