Add FastAPI framework support to Oryx

[Saipriya-1144]

This PR onboards FastAPI as a first-class detected framework in Oryx, alongside Django and Flask.

How detection works
During startup, the script generator scans the app directory for common entry files — main.py, app.py, application.py, server.py — and looks for "from fastapi import" or "FastAPI(" in their contents. Detection runs in priority order: Django → FastAPI → Flask, so if an app somehow imports both FastAPI and Flask, FastAPI wins.

How the app starts
Once detected, Oryx generates a Gunicorn startup command with Uvicorn workers:

gunicorn --timeout 600 --access-logfile '-' --error-logfile '-' -c /opt/startup/gunicorn.conf.py --chdir=/tmp/8dea620f57fccb8" gunicorn -k uvicorn_worker.UvicornWorker main:app

FastAPI is ASGI, so it needs Uvicorn workers instead of Gunicorn's default sync workers. Gunicorn acts as the process manager (timeouts, restarts, worker scaling) while Uvicorn handles the async protocol.

Debug mode
In debug mode, Oryx skips Gunicorn entirely and runs:

python -m debugpy --listen 0.0.0.0:5678 -m uvicorn main:app --host 0.0.0.0 --port 8000Added Go startup script generator tests to unit-tests.yaml — they now run on every PR and push to main.

Added Go startup script generator tests to unit-tests.yaml — they now run on every PR and push to main.

Testing:
Created a runtime image with these changes and deployed a fastapi app

For python 3.14:

For python 3.13:
Deployed the same fastapi app as above, but it detected the app as flask - as expected

Debug mode:

• The purpose of this PR is explained in this message or in an issue. If an issue please include a reference as #<issue_number>.
• Tests are included and/or updated for code changes.
• Proper license headers are included in each file.