feat: add prompt lru cache

[immorez]

Description

This PR introduces a generic LRU (Least Recently Used) cache implementation with utility functions to handle caching efficiently. The changes include:

1. LRU Cache Class:

   • A generic LRUCache class that supports key-value pairs with a configurable maximum size.
   • Implements LRU eviction policy to remove the least recently used items when the cache exceeds the maximum size.

2. Utility Functions:

   • createLRUCache: A factory function to create LRU cache instances.
   • Integration with the existing normalizeText and extractPromptCacheKey functions for the prompt caching use case.

3. Fixes:

   • Resolved a type safety issue in the cache eviction logic by properly handling iterator results.

Changes

• Added LRUCache class with get, set, clear, and has methods.
• Added factory function createLRUCache for easy cache creation.
• Updated the prompt cache implementation to use the new LRU cache.
• Fixed type safety in the cache eviction logic.