Add experimental `uv sync --output-format json` (#13689)
This is a continuation of the work in
* #12405
I have:
* moved to an architecture where the human output is derived from the
json structs to centralize more of the printing state/logic
* cleaned up some of the names/types
* added tests
* removed the restriction that this output is --dry-run only
I have not yet added package info, which was TBD in their design.
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Co-authored-by: x0rw <mahdi.svt5@gmail.com>
Co-authored-by: Zanie Blue <contact@zanie.dev>
Co-authored-by: John Mumm <jtfmumm@gmail.com>
