Add way to get coin states in batches

[Rigidity]

Purpose:

When added to the wallet protocol, this will allow wallets to sync their coin state efficiently in batches rather than downloading all of the state in a single response (which can fail if it's too large).

Testing Notes:

There is a unit test for ensuring that it successfully fetches the correct number of coins with a high volume of puzzle hashes (including with filters enabled and disabled), and another for high coin record count.

[coveralls-official]

Pull Request Test Coverage Report for Build 7626699349

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• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 90.662%

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Totals
Change from base Build 7574540476:	0.07%
Covered Lines:	94966
Relevant Lines:	104713

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💛 - Coveralls

[arvidn]

maybe it would make sense to generate the coins in height order instead, and compare them directly to what you get back from the coin store, without sorting the coin states by amount.

The main challenge would be the cut in the middle where you need to make another request batch

[emlowe]

Would also be useful to look into why the tests don't exercise line 495 as the coverage diff reports

[arvidn]

I think the fixture is an important change to make.
I'm also not convinced you test the include_hints case. The SQL query is quite complex, I'm not confident that I can tell that it's correct (until we have a solid test)

[arvidn]

looks good! Feel free to resolve my comments. Maybe we should let Earle have another pass before we land as well