Implement ES2021 FinalizationRegistry with cleanupSome

This PR implements the ES2021 FinalizationRegistry constructor and prototype,
allowing JavaScript code to register cleanup callbacks that are called when
objects are garbage collected.

## Features
- Complete ES2021 FinalizationRegistry implementation
- All three required methods: register(), unregister(), and cleanupSome()
- ES2023 symbols-as-weakmap-keys support (unregistered symbols can be held weakly)
- Thread-safe implementation using ConcurrentHashMap and ReferenceQueue
- Comprehensive test suite with 40+ tests

## Implementation Notes
- Uses Java's ReferenceQueue for garbage collection detection
- Follows the same validation patterns as NativeWeakMap for consistency
- Implements using the LambdaConstructor pattern
- Properly validates targets according to the CanBeHeldWeakly specification
- cleanupSome() method supports optional callback parameter per spec

Closes #2057

Author: anivar