perf: vote state view

[jstarry]

Problem

The stakes cache stores copies of vote account data so that things like consensus, inflation rewards, and vote timestamp calculation can access the vote account state for all staked validators. Every time when a vote is processed, the vote account entry in the stakes cache is updated and the account data is deserialized and ~1KB is allocated to store the new state. This is all unnecessary because the vote state data the protocol needs can be read on demand directly from the account data byte vector.

Summary of Changes

• Introduce new VoteStateView type which stores a copy of the vote account's Arc<Vec<u8>> and field offset data to speed up vote state field lookups.

Fixes #

[mergify]

If this PR represents a change to the public RPC API:

1. Make sure it includes a complementary update to rpc-client/ (example)
2. Open a follow-up PR to update the JavaScript client @solana/web3.js (example)

Thank you for keeping the RPC clients in sync with the server API @jstarry.

[mergify]

The Firedancer team maintains a line-for-line reimplementation of the
native programs, and until native programs are moved to BPF, those
implementations must exactly match their Agave counterparts.
If this PR represents a change to a native program implementation (not
tests), please include a reviewer from the Firedancer team. And please
keep refactors to a minimum.

[jstarry]

Before

test bench_vote_account_try_from ... bench:         321.63 ns/iter (+/- 5.15)

After

test bench_vote_account_try_from ... bench:          59.46 ns/iter (+/- 0.18)