Support custom cache_control blocks with TTL configuration for Anthropic models

[jainaayush01]

Problem: Current implementation always strips existing cache_control and applies default ephemeral caching
Proposed Solution: Check for existing cache_control blocks and preserve them, with optional TTL config
Use Case: Advanced users want control over cache duration and which messages are cached
Compatibility: Maintains backward compatibility - defaults to current behavior

[jainaayush01]

@danny-avila i'm open to working on this issue,

Anthropic directly supports prompt caching with 5m and 1hr ttl configs, on production it makes more sense to have 1hr ttl for system prompts and tools and helps reduce the cost drastically.

I would also like to know the contributing guidelines for this repo or should i follow similar approach to that of LibreChat

Thank you for the work that you have been doing!