Add uv workspace list --paths

[zanieb]

I initially thought I didn't need this, but in some contexts, the workspace member name is not useful at all and I just want to iterate over the paths without composing with uv workspace dir --package <name>

[zanieb]

Otherwise, the code I'm replacing looks like

index b66739d4..b15e6d79 100644
--- a/.../runner.py
+++ b/.../runner.py
@@ -45,13 +45,21 @@
 
 def find_workspace_members() -> Generator[pathlib.Path]:
     """Yield the root directories of all workspace members with tests."""
-    # TODO(zanieb): Use `uv metadata` for workspace member discovery once that exists
-    for path in WORKSPACE_ROOT.glob("foo-*/pyproject.toml"):
-        member_root = path.parent
-        if not (member_root / "tests").is_dir():
-            continue
-
-        yield member_root
+    output = subprocess.check_output(
+        ["uv", "workspace", "list", "--preview"], cwd=WORKSPACE_ROOT
+    )
+    for member in output.decode().splitlines():
+        member_root = (
+            subprocess.check_output(
+                ["uv", "workspace", "dir", "--preview", "--package", member],
+                cwd=WORKSPACE_ROOT,
+            )
+            .decode()
+            .strip()
+        )
+        path = pathlib.Path(member_root)
+        if (path / "tests").is_dir():
+            yield path
 

[zsol]

I was going to suggest listing both names and paths, but I realized paths are more powerful (one can always cd into it and look up the name).
Thoughts about changing the default to list paths and have a --names option instead?

[zanieb]

You can also compose it the other direction, e.g., uv workspace dir --package <name>. I'm not sure one is inherently more powerful than the other. I find the names a little friendlier for the default output / consistent with the rest of uv.