make GlobalMemo and GlobalSignal not copy or clone

packages/signals/src/effect.rs

@@ -127,7 +127,7 @@ impl Effect {
     ///
     /// The signal will be owned by the current component and will be dropped when the component is dropped.
     pub fn new(callback: impl FnMut() + 'static) -> Self {
-        let mut myself = Self {
+        let myself = Self {
             source: current_scope_id().expect("in a virtual dom"),
             inner: EffectInner::new(Box::new(callback)),
         };