path-uri: clarify host-native path conversion (#29501)

## Why

Downstream refactors are producing confusing code with this
functionality having a very generic name. Encoding the specific
conversion approach in the method name makes it clearer.

## What

Rename `PathUri::from_path` to `PathUri::from_host_native_path` and
update its Rust call sites.

codex-rs/utils/path-uri/src/lib.rs

@@ -121,7 +121,7 @@ impl PathUri {
     /// Relative paths are reported as invalid input. Absolute paths without a
     /// valid URI representation use the fallback documented on
     /// [`Self::from_abs_path`].
-    pub fn from_path(path: impl AsRef<Path>) -> io::Result<Self> {
+    pub fn from_host_native_path(path: impl AsRef<Path>) -> io::Result<Self> {
         let path = AbsolutePathBuf::from_absolute_path_checked(path)
             .map_err(|err| io::Error::new(io::ErrorKind::InvalidInput, err))?;
         Ok(Self::from_abs_path(&path))