New author tutorials

[daniel-prefect]

This PR updates the quickstart and adds three new tutorials. These four tutorials collectively serve as a tutorial series to get developers up to speed on Prefect, though they're written in such a way that a developer can start with any of them.

• Quickstart (simplifies the flow example and focuses on the first run experience)
  • Closes https://linear.app/prefect/issue/DOC-94/simplify-the-existing-quickstart-tutorial-and-target-it-at-the-author
• Schedule a flow (extracts the work pool, deployment, and scheduling content from the quickstart into its own tutorial)
  • Closes https://linear.app/prefect/issue/DOC-100/create-an-author-tutorial-for-scheduling
• Build a data pipeline (improves the flow from the quickstart by making it more robust and performant)
  • Closes https://linear.app/prefect/issue/DOC-101/create-an-author-tutorial-for-data-pipelines
• Extract data from websites (introduces techniques for dealing with unstructured data and big data, code TBD)
  • Closes https://linear.app/prefect/issue/DOC-99/create-an-author-tutorial-for-web-scraping

Checklist

• This pull request references any related issue by including "closes <link to issue>"
• If this pull request adds new functionality, it includes unit tests that cover the changes
• If this pull request removes docs files, it includes redirect settings in mint.json.
• If this pull request adds functions or classes, it includes helpful docstrings.