Add chat history to QAChain

[anyxling]

Description

This new feature enables context-aware query generation by integrating chat history with the LLM.

from langchain_arangodb import ArangoGraphQAChain
from arango import ArangoClient

# Connect to ArangoDB
db = ArangoClient().db(...)

# Initialize components
graph = ArangoGraph()
llm = ChatOpenAI(model="gpt-4o", temperature=0)  # Replace with your LLM

# Create chat message history
history = ArangoChatMessageHistory(
    session_id="user_123",
    db=db,
    collection_name="chat_sessions"
)

# Create the chain
chain = ArangoGraphQAChain.from_llm(
    llm=llm, 
    graph=graph, 
    allow_dangerous_requests=True, 
    verbose=True,
    include_history=True,
    chat_history_store=history,
    max_history_messages=10,
)

Type of Change

• New feature
• Bug fix
• Breaking change
• Project configuration change

Complexity

Note

Please provide an estimated complexity of this PR of either Low, Medium or High

How Has This Been Tested?

• Unit tests
• Integration tests
• Manual tests

Checklist

• Unit tests updated
• Integration tests updated
• CHANGELOG.md updated

[aMahanna]

LGTM