Implement Deref and DerefMut for In (#11104)

# Objective

Implement Deref and DerefMut for In<T>

makes it so the user doesn't have to add ".0" in most cases

crates/bevy_ecs/src/system/mod.rs

@@ -308,6 +308,20 @@ pub fn assert_system_does_not_conflict<Out, Params, S: IntoSystem<(), Out, Param
     system.run((), &mut world);
 }
 
+impl<T> std::ops::Deref for In<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T> std::ops::DerefMut for In<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::any::TypeId;