Add PartialEq and Hash reflections for AnimationNodeIndex (#18718)

# Objective

Fixes #18701

## Solution

Add reflection of `PartialEq` and `Hash` to `AnimationNodeIndex`

## Testing

Added a new `#[test]` with the minimal reproduction posted on #18701.

Author: hukasu

crates/bevy_animation/src/lib.rs

@@ -1533,6 +1533,8 @@ impl<'a> Iterator for TriggeredEventsIter<'a> {
 
 #[cfg(test)]
 mod tests {
+    use bevy_reflect::{DynamicMap, Map};
+
     use super::*;
 
     #[derive(Event, Reflect, Clone)]
@@ -1664,4 +1666,13 @@ mod tests {
         active_animation.update(clip.duration, clip.duration); // 0.3 : 0.0
         assert_triggered_events_with(&active_animation, &clip, [0.3, 0.2]);
     }
+
+    #[test]
+    fn test_animation_node_index_as_key_of_dynamic_map() {
+        let mut map = DynamicMap::default();
+        map.insert_boxed(
+            Box::new(AnimationNodeIndex::new(0)),
+            Box::new(ActiveAnimation::default()),
+        );
+    }
 }

crates/bevy_reflect/src/impls/petgraph.rs

@@ -3,6 +3,8 @@ use crate::{impl_reflect_opaque, prelude::ReflectDefault, ReflectDeserialize, Re
 impl_reflect_opaque!(::petgraph::graph::NodeIndex(
     Clone,
     Default,
+    PartialEq,
+    Hash,
     Serialize,
     Deserialize
 ));