feat: add targetVersion and known module import classification options

[apcamargo]

This PR introduces three new options:

• targetVersion (e.g.: "py312" or "default") sets the Python version the code targets. Formatting and import sorting then follow that version.
• knownFirstParty and knownThirdParty control which section imports sort into. This is important because the dprint plugin does not perform automatic identification of first-party modules like ruff does, so we should allow the user to at least input that manually.

This is a follow up to #22

This PR is AI-assisted, but I did perform a couple of reviews and could not find any issue.

[apcamargo]

@dsherret ready for review