feat: add some helpers to use_ref

examples/use_ref.rs

@@ -0,0 +1,21 @@
+use std::collections::HashMap;
+
+use dioxus::prelude::*;
+fn main() {}
+
+fn app(cx: Scope) -> Element {
+    let val = use_ref(&cx, || HashMap::<u32, String>::new());
+
+    // Pull the value out locally
+    let p = val.read();
+
+    // to get an &HashMap we have to "reborrow" through the RefCell
+    // Be careful: passing this into children might cause a double borrow of the RefCell and a panic
+    let g = &*p;
+
+    cx.render(rsx! {
+        div {
+            "hi"
+        }
+    })
+}