uplift: Add validators package from evm repositories

[JonathanOppenheimer]

Why this should be merged

There are packages in subnet-evm and coreth that share a lot of functionality / are mirrored. These packages should be uplifted to AvalancheGo to prevent the duplicative maintenance of two sets of the same code. This is part of that effort, specifically in assisting the uplifting of the warp package. Closes #4207

Validators has no external imports but there are a couple things worth noting:

• validators/locked_reader.go is similar to snow/uptime.LockedCalculator (thread-safe reads) but not a duplicate: it also returns validator metadata atomically with uptime.
• There is a minor name overlap with validatorData it exists in proposervm but with different fields and in a different package

How this was tested

This is currently 'dead' code; after a new AvalancheGo release is dropped, we can use the code in the evm repositories.

Need to be documented in RELEASES.md?

No

[Copilot]

Pull Request Overview

This PR uplifts the validators package from subnet-evm and coreth repositories to AvalancheGo to prevent duplicative maintenance of shared functionality, specifically to assist in uplifting the warp package.

• Adds a complete validators package with state management, uptime tracking, and manager functionality
• Implements pausable uptime management that can pause/resume validator tracking based on active status
• Provides thread-safe validator reader with atomic uptime and metadata retrieval

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
vms/evm/plugin/validators/manager.go	Core manager implementation for validator state and uptime synchronization
vms/evm/plugin/validators/state/state.go	Validator state CRUD operations with database persistence
vms/evm/plugin/validators/uptime/pausable_manager.go	Pausable uptime manager that wraps AvalancheGo's uptime manager
vms/evm/plugin/validators/locked_reader.go	Thread-safe reader for atomic validator and uptime retrieval
vms/evm/plugin/validators/interfaces/	Interface definitions for manager, state, and uptime components
vms/evm/plugin/validators/state/codec.go	Serialization codec for validator data persistence
vms/evm/plugin/validators/README.md	Comprehensive documentation of the validators package
Test files	Comprehensive test coverage for all components

[joshua-kim]

This package (everything under validators/) has a ton of sprawl - I think we could reasonably put this under one file. We need to figure out a package name/type name.... maybe something like evm/state/validators.go? I'm not sure what plugin means in this context.

[JonathanOppenheimer]

Let's discuss the structure after the code clean up first - think it'll make more sense then as I'm sure a lot of stuff will change / get deleted etc.

plugin is the name from the EVM repositories.