Move preview features into a dedicated crate (#15482)

## Summary

This is causing some cyclic dependencies issues for me, because these
can be used in virtually _any_ crate (like `uv-install-wheel`), which
then means that all of `uv-configuration` becomes a dependency, etc. I
think this should be a leaf crate so that we can safely depend on it
anywhere.

crates/uv-python/src/managed.rs

@@ -13,7 +13,7 @@ use itertools::Itertools;
 use same_file::is_same_file;
 use thiserror::Error;
 use tracing::{debug, warn};
-use uv_configuration::{Preview, PreviewFeatures};
+use uv_preview::{Preview, PreviewFeatures};
 #[cfg(windows)]
 use windows_sys::Win32::Storage::FileSystem::FILE_ATTRIBUTE_REPARSE_POINT;