Supporting running FastAPI apps via Uvicorn in Python runtimes

[cormacpayne]

This PR adds support for detecting and running applications targeting the FastAPI Python framework. Rather than using the traditional Gunicorn server for running the application, we are now supporting Uvicorn as the server of choice for FastAPI applications.

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