vote-program: deserialize, check initialized, then convert

[buffalojoec]

Problem

As per the amendment to SIMD-0185 in solana-foundation/solana-improvement-documents#369, when the vote state v4 feature gate is active, the Vote program must adjust the way it handles its "deserialize and convert" workflow.

With the vote state v4 feature disabled, a handful of program instructions call VoteStateV3::deserialize, which coerces the underlying vote state to v3, before checking its initialization status. These instructions are:

• Authorize*
• UpdateValidatorIdentity
• UpdateCommission
• Withdraw

Only when the vote state v4 feature is enabled should the behavior change to "deserialize -> check initialized -> convert", as per solana-foundation/solana-improvement-documents#369.

Summary of Changes

First, refactors the verify_and_get_vote_state_handler helper to deserialize as VoteStateVersions first, then check for initialization, then convert to v3 or v4.

Then, configures instructions that did not previously call this helper (Authorize*, UpdateValidatorIdentity, UpdateCommission, Withdraw) to conditionally call it based on the feature status.

[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.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.96774% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.1%. Comparing base (a87fd3e) to head (3806b2d).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master    #8524     +/-   ##
=========================================
- Coverage    83.1%    83.1%   -0.1%     
=========================================
  Files         849      849             
  Lines      368587   368644     +57     
=========================================
+ Hits       306604   306649     +45     
- Misses      61983    61995     +12     

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