change(rpc): Add value pool balances to getblockchaininfo RPC method response

[arya2]

Motivation

We want to add value pool balances at the chain tip to Zebra's getblockchaininfo RPC method response.

Closes #8767.

Specifications & References

https://zcash.github.io/rpc/getblockchaininfo.html

Solution

• Moves the Zec type in zebra-rpc out from behind the getblocktemplate-rpcs feature flag.
• Adds a ValuePoolBalance type to a new types::get_blockchain_info module with a fn for creating one from a ValueBalance.
• Updates the getblockchaininfo RPC method return type to a BoxFuture to make async calls to the state service.
• Adds a new state service request for getting the tip height, tip hash, and the value balance.
  • Checks that the tip hasn't changed while reading the value balance from the finalized state. This could cause the RPC method to return an error after a few retries, which could be avoided by adding the value balance information to the ChainTipBlock instead of adding a new state service request, but in practice, the tip and value balance should be in-memory when there is no non-finalized best chain and blocks are being committed rapidly, so it should be unlikely to return that error. Still, let me know if we want to add it to the ChainTipBlock instead, we could do that here or in a follow-up PR.
• Updates the getblockchaininfo method to get the chain tip height, hash, value balance, and block time from state requests.
• Updates snapshots

Related Changes:

• Minor refactor of estimated_height assignment
• Uses generic error construction in the last couple places where possible and removes the outdated TODOs

Tests

Updates existing snapshots (and some prop tests to handle the BoxFuture wrapped return type).

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.

[oxarbitrage]

Looks really good to me, great work, thanks!

[oxarbitrage]

It seems the tests are hang somewhere so the CI is giving up. https://github.com/ZcashFoundation/zebra/actions/runs/10414872254/job/28844504197?pr=8769

I am having the same issue locally when running the suite:

cargo test

[arya2]

It seems the tests are hang somewhere so the CI is giving up

Ah, yes, I forgot to handle the mock service requests in the prop tests.