feat: create chat engine folder for python

questions.ts

templates/components/vectordbs/python/none/constants.py

templates/components/vectordbs/python/none/context.py

templates/components/vectordbs/python/none/generate.py

templates/components/vectordbs/python/none/index.py

templates/index.ts

templates/types/simple/fastapi/app/api/routers/chat.py

templates/types/simple/fastapi/app/engine/index.py

templates/types/streaming/fastapi/app/context.py

templates/types/streaming/fastapi/app/engine/__init__.py

templates/types/streaming/fastapi/app/engine/index.py