rpc(getblock): Add value pools output

[oxarbitrage]

Motivation

We want the lockbox value pool information in the getblock output for a given block

The lockbox information was added in zcashd at zcash/zcash#6912, It is part of a list of pools that this PR adds to Zebra.

#8730

Specifications & References

zcash/zcash#6912

Solution

The solution implements the valuePools object and some of the fields. In zcashd this is like:

...
  "valuePools": [
    {
      "id": "transparent",
      "monitored": true,
      "chainValue": 0.03437500,
      "chainValueZat": 3437500,
      "valueDelta": 0.00625000,
      "valueDeltaZat": 625000
    },
 ...

Where valueDelta is the value pool for the requested block but chainValue is the value pool up to the requested blocks. Zebra do not keep track of value pools at specific heights for the finalized chain so i think we can't have that value. I am open to suggestions here.

Solution implements id, valueDelta and valueDeltaZat for each pool including the lockbox

Tests

Snapshot tests added by now.

Follow-up Work

Need zcashd diff tests.

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.

[arya2]

This PR looks great, though it seems zcashd is returning the total chain value balances at the provided heights, so we may need another PR to track those in Zebra first.

[arya2]

Optional/Nitpick: This Default impl could be derived.

[oxarbitrage]

Closed as it is not critical and much more work than expected.

[arya2]

This type needs to be moved out from behind the getblocktemplate-rpcs feature flag.

[arya2]

This looks good to merge once the Zec type has been moved.