Remove `HydrationKey` from `leptos_reactive`

leptos_reactive/src/scope.rs

@@ -330,26 +330,4 @@ impl fmt::Debug for ScopeDisposer {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_tuple("ScopeDisposer").finish()
     }
-}
-
-/// This struct is used for hydrating the leptos views from the DOM.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
-pub struct HydrationKey(pub usize);
-
-impl HydrationKey {
-    /// Converts the [`HydrationKey`] into a string, suitable for
-    /// SSR or looking up the node for hydration.
-    pub fn to_string(&self, closing: bool) -> String {
-        #[cfg(debug_assertions)]
-        return format!("_{}{}", self.0, if closing { 'c' } else { 'o' });
-
-        #[cfg(not(debug_assertions))]
-        return format!("_{}", self.0);
-    }
-}
-
-impl fmt::Display for HydrationKey {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> std::fmt::Result {
-        self.0.fmt(f)
-    }
-}
+}