feat: option to build directly with uv (#2322)

* feat: option to build directly with uv

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

tests: add uv to tests

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

fix: uv doesn't pick special Pythons at the top of the path

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

fix: set uv build constraints too

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

fix: uv doesn't support PyPy 3.8

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

tests: add pyproject.toml for failing test

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

Revert "tests: add pyproject.toml for failing test"

This reverts commit 619bde368a67dfdd8f02dc33a1525c27bc8cbe91.

tests: skip uv output test

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* tests: uv was in the wrong fixture

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* fix: from @trim21

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* tests: improve skipping

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* fix: some fixes from copilot review

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

unit_test/options_test.py

@@ -328,6 +328,11 @@ def test_environment_pass_references():
             "build",
             [],
         ),
+        (
+            'build-frontend = "uv"',
+            "uv",
+            [],
+        ),
         (
             'build-frontend = {name = "build"}',
             "build",