bevy_reflect: Reflect &'static str (bevyengine#11686)

# Objective

`&'static str` doesn't implement `Reflect`. I don't think this was
intentionally excluded.

## Solution

Make `&'static str` implement `Reflect`.

---

## Changelog

- Implement `Reflect` and friends for `&'static str`
- Add missing `Reflect::debug` implementation for `Cow<'static, str>`

crates/bevy_reflect/src/impls/std.rs

@@ -1111,6 +1111,10 @@ impl Reflect for Cow<'static, str> {
             Some(false)
         }
     }
+
+    fn debug(&self, f: &mut fmt::Formatter<'_>) -> core::fmt::Result {
+        fmt::Debug::fmt(self, f)
+    }
 }
 
 impl Typed for Cow<'static, str> {
@@ -1305,6 +1309,108 @@ impl<T: FromReflect + Clone + TypePath> FromReflect for Cow<'static, [T]> {
     }
 }
 
+impl Reflect for &'static str {
+    fn get_represented_type_info(&self) -> Option<&'static TypeInfo> {
+        Some(<Self as Typed>::type_info())
+    }
+
+    fn into_any(self: Box<Self>) -> Box<dyn Any> {
+        self
+    }
+
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
+    fn into_reflect(self: Box<Self>) -> Box<dyn Reflect> {
+        self
+    }
+
+    fn as_reflect(&self) -> &dyn Reflect {
+        self
+    }
+
+    fn as_reflect_mut(&mut self) -> &mut dyn Reflect {
+        self
+    }
+
+    fn apply(&mut self, value: &dyn Reflect) {
+        let value = value.as_any();
+        if let Some(&value) = value.downcast_ref::<Self>() {
+            *self = value;
+        } else {
+            panic!("Value is not a {}.", Self::type_path());
+        }
+    }
+
+    fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>> {
+        *self = value.take()?;
+        Ok(())
+    }
+
+    fn reflect_ref(&self) -> ReflectRef {
+        ReflectRef::Value(self)
+    }
+
+    fn reflect_mut(&mut self) -> ReflectMut {
+        ReflectMut::Value(self)
+    }
+
+    fn reflect_owned(self: Box<Self>) -> ReflectOwned {
+        ReflectOwned::Value(self)
+    }
+
+    fn clone_value(&self) -> Box<dyn Reflect> {
+        Box::new(*self)
+    }
+
+    fn reflect_hash(&self) -> Option<u64> {
+        let mut hasher = reflect_hasher();
+        Hash::hash(&std::any::Any::type_id(self), &mut hasher);
+        Hash::hash(self, &mut hasher);
+        Some(hasher.finish())
+    }
+
+    fn reflect_partial_eq(&self, value: &dyn Reflect) -> Option<bool> {
+        let value = value.as_any();
+        if let Some(value) = value.downcast_ref::<Self>() {
+            Some(std::cmp::PartialEq::eq(self, value))
+        } else {
+            Some(false)
+        }
+    }
+
+    fn debug(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self, f)
+    }
+}
+
+impl Typed for &'static str {
+    fn type_info() -> &'static TypeInfo {
+        static CELL: NonGenericTypeInfoCell = NonGenericTypeInfoCell::new();
+        CELL.get_or_set(|| TypeInfo::Value(ValueInfo::new::<Self>()))
+    }
+}
+
+impl GetTypeRegistration for &'static str {
+    fn get_type_registration() -> TypeRegistration {
+        let mut registration = TypeRegistration::of::<Self>();
+        registration.insert::<ReflectFromPtr>(FromType::<Self>::from_type());
+        registration.insert::<ReflectFromReflect>(FromType::<Self>::from_type());
+        registration
+    }
+}
+
+impl FromReflect for &'static str {
+    fn from_reflect(reflect: &dyn crate::Reflect) -> Option<Self> {
+        reflect.as_any().downcast_ref::<Self>().copied()
+    }
+}
+
 impl Reflect for &'static Path {
     fn get_represented_type_info(&self) -> Option<&'static TypeInfo> {
         Some(<Self as Typed>::type_info())
@@ -1735,4 +1841,11 @@ mod tests {
         let output = <&'static Path as FromReflect>::from_reflect(&path).unwrap();
         assert_eq!(path, output);
     }
+
+    #[test]
+    fn static_str_should_from_reflect() {
+        let expected = "Hello, World!";
+        let output = <&'static str as FromReflect>::from_reflect(&expected).unwrap();
+        assert_eq!(expected, output);
+    }
 }