Implement Reflect for ParsedPath, OffsetAccess, and Access

[tauanbinato]

Objective

• Fixes Implement Reflect for ParsedPath #22974

Solution

• Implemented Reflect for ParsedPath, OffsetAccess, and Access<'static>. Access<'static> is reflected as an opaque type via impl_reflect_opaque! since the lifetime parameter prevents using #[derive(Reflect)] directly. OffsetAccess and ParsedPath use #[derive(Reflect)] since their fields (including Access<'static>) all implement Reflect.

Testing

• All existing bevy_reflect tests pass. Path-related doctests pass. Verified the types compile with Reflect derived.

[jhgarner]

Is it possible to reflect it as an Enum instead of an Opaque? Without the Enum implementation, using reflect to serialize/deserialize this will be more awkward. With the Enum implementation, everything should line up since Cow<'static, T> implements Reflect and the Serialize/Deserialize traits.

[tauanbinato]

Good point, reflecting as an Enum would be better for serialization. I went with Opaque because of the lifetime on Access<'a>, but since we already constrain it to 'static and OffsetAccess only uses Access<'static>, it should be doable. Do you think it's worth trying to derive Reflect as an enum here?

[jhgarner]

Thanks for starting on this. Since you closed this PR, I created my own attempt at #23371. It looks like everything just worked correctly using the Reflect derive macro even with the lifetime parameter. Let me know if I missed something though.