implement ConversationalMemoryBuffer

[K-Schubert]

Description

Implement ConversationalMemoryBuffer class.

Implementation

• Implement RedisMemoryHandler for fast memory retrieval from Redis db. Gets conversation history from user_uuid and conversation_uuid.
• Implement PostgresMemoryHandler to index chat message in chat_history table.
• Implement BaseMemory class to manage RedisMemoryHandler and PostgresMemoryHandler.
• Implement ConversationalMemoryBuffer which tracks last k_memory conversation turns.
• Implement ConversationalMemory to wrap memory functionality.
• Instantiate chat_memory attribute in RAGProcessor.