added streaming fastapi template

templates/.gitignore

templates/streaming/fastapi/README-template.md

templates/streaming/fastapi/app/__init__.py

templates/streaming/fastapi/app/api/__init__.py

templates/streaming/fastapi/app/api/routers/__init__.py

templates/streaming/fastapi/app/api/routers/chat.py

templates/streaming/fastapi/data/brk-2022.pdf

templates/streaming/fastapi/gitignore

templates/streaming/fastapi/main.py

templates/streaming/fastapi/pyproject.toml

templates/streaming/fastapi/tests/__init__.py