SystemId should manually implement Eq (#12436)

# Objective

`System<f32>` currently does not implement `Eq` even though it should

## Solution

Manually implement `Eq` like other traits are manually implemented

Author: eira-fransham

crates/bevy_ecs/src/system/system_registry.rs

@@ -38,9 +38,11 @@ impl<I, O> RemovedSystem<I, O> {
 ///
 /// These are opaque identifiers, keyed to a specific [`World`],
 /// and are created via [`World::register_system`].
-#[derive(Eq)]
 pub struct SystemId<I = (), O = ()>(Entity, std::marker::PhantomData<fn(I) -> O>);
 
+// A manual impl is used because the trait bounds should ignore the `I` and `O` phantom parameters.
+impl<I, O> Eq for SystemId<I, O> {}
+
 // A manual impl is used because the trait bounds should ignore the `I` and `O` phantom parameters.
 impl<I, O> Copy for SystemId<I, O> {}