Project root detection logic leads to configuration duplication in some circumstances about ufmt

[amyreese]

The current behavior is specifically designed with a monorepo in mind, though more from the perspective of embedding third party/OSS packages into a larger repo, where stopping at the nearest pyproject.toml ensures that formatting a file "internally" will have the same behavior as formatting the file externally on CI or a standalone checkout, regardless of whether the monorepo uses custom formatting options for everything outside of the third party imports. Granted, that behavior is then suboptimal for projects that contain multiple related packages, each with their own subdirectory and pyproject.toml.

The former use case is one that I have a vested interest in maintaining; the latter is one that I'm sympathetic to, but haven't personally run into, and I'm not really sure how to find a good compromise between these two use cases, and their needs seem somewhat opposed. I'm open to ideas though.

That said, I think that adding a --root option would be a simple step forward, and the cwd case could be handled by passing --root=..