Spring-ai GH-1240: Add builder pattern to ChromaVectorStore for better initiali…

…zation control

Fixes: #1240

Issue: https://github.com/spring-projects/spring-ai/issues/1240

The change addresses initialization issues when ChromaVectorStore is used outside Spring context, particularly in scenarios where collections are created manually before store instantiation. Previously, collection ID wasn't properly populated when afterPropertiesSet() wasn't called by Spring container.

• Add builder pattern to ChromaVectorStore for better initialization control
• Add initialization flag to prevent multiple collection creation calls
• Add integration tests for builder pattern usage scenarios
• Add spring-ai-transformers dependency for testing
• Remove unused constants (SIMILARITY_THRESHOLD_ALL, DEFAULT_TOP_K)

Collection ID is now properly set regardless of whether the store is managed by Spring or created manually, solving the 404 Not Found errors during document insertion.

Comment From: markpollack

merged in c8a9b1640a66d022c02323dfe600b0fabb3c5cb5