change(scan): Create a function that scans one block by height, and stores the results in the database

[teor2345]

Motivation

This is a quick follow up to a bunch of recent scanner changes.

@upbqdn or @oxarbitrage this might conflict with what you're working on, but I'm happy to re-do it, because your PRs are actually changing things.

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Solution

• Create a function that scans one block by height, gets it from the state, and puts the results in the database
• Add some TODOs and update some function comments

Most of these arguments are cheap to clone, but if we have a lot of keys the key sets could be very large, so I used Arc.

Testing

This is just a cleanup of the previous PR.

Review

This is a routine cleanup.

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[teor2345]

Just an import merge conflict, should be fixed now.