Avoid calling normalize_path with relative paths that extend beyond the current directory (#3013)

## Summary

It turns out that `normalize_path` (sourced from Cargo) has a subtle
bug. If you pass it a relative path that traverses beyond the root, it
silently drops components. So, e.g., passing `../foo/bar`, it will just
drop the leading `..` and return `foo/bar`.

This PR encodes that behavior as a `Result` and avoids using it in such
cases.

Closes https://github.com/astral-sh/uv/issues/3012.

crates/uv-interpreter/src/interpreter.rs

@@ -488,12 +488,10 @@ impl InterpreterInfo {
     /// unless the Python executable changes, so we use the executable's last modified
     /// time as a cache key.
     pub(crate) fn query_cached(executable: &Path, cache: &Cache) -> Result<Self, Error> {
-        let executable_bytes = executable.as_os_str().as_encoded_bytes();
-
         let cache_entry = cache.entry(
             CacheBucket::Interpreter,
             "",
-            format!("{}.msgpack", digest(&executable_bytes)),
+            format!("{}.msgpack", digest(&executable)),
         );
 
         let modified = Timestamp::from_path(uv_fs::canonicalize_executable(executable)?)?;