Impl Reflect for PathBuf and OsString (bevyengine#6193)

# Objective

`Reflect` impl is missing for `PathBuf` and `OsString`. Closes bevyengine#6166.

## Solution

Add implementations.

---

## Changelog

### Added

`Reflect` impls for `PathBuf` and `OsString`.

crates/bevy_reflect/src/impls/std.rs

@@ -11,6 +11,8 @@ use crate::utility::{GenericTypeInfoCell, NonGenericTypeInfoCell};
 use bevy_reflect_derive::{impl_from_reflect_value, impl_reflect_value};
 use bevy_utils::{Duration, Instant};
 use bevy_utils::{HashMap, HashSet};
+#[cfg(any(unix, windows))]
+use std::ffi::OsString;
 use std::{
     any::Any,
     borrow::Cow,
@@ -20,6 +22,7 @@ use std::{
         NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize,
     },
     ops::{Range, RangeFrom, RangeFull, RangeInclusive, RangeTo, RangeToInclusive},
+    path::PathBuf,
 };
 
 impl_reflect_value!(bool(Debug, Hash, PartialEq, Serialize, Deserialize));
@@ -39,6 +42,7 @@ impl_reflect_value!(isize(Debug, Hash, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(f32(Debug, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(f64(Debug, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(String(Debug, Hash, PartialEq, Serialize, Deserialize));
+impl_reflect_value!(PathBuf(Debug, Hash, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(Result<T: Clone + Reflect + 'static, E: Clone + Reflect + 'static>());
 impl_reflect_value!(HashSet<T: Hash + Eq + Clone + Send + Sync + 'static>());
 impl_reflect_value!(Range<T: Clone + Send + Sync + 'static>());
@@ -62,6 +66,11 @@ impl_reflect_value!(NonZeroU16(Debug, Hash, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(NonZeroU8(Debug, Hash, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(NonZeroI8(Debug, Hash, PartialEq, Serialize, Deserialize));
 
+// Only for platforms that can serialize it as in serde:
+// https://github.com/serde-rs/serde/blob/3ffb86fc70efd3d329519e2dddfa306cc04f167c/serde/src/de/impls.rs#L1732
+#[cfg(any(unix, windows))]
+impl_reflect_value!(OsString(Debug, Hash, PartialEq, Serialize, Deserialize));
+
 impl_from_reflect_value!(bool);
 impl_from_reflect_value!(char);
 impl_from_reflect_value!(u8);