add must use to several hooks

packages/hooks/src/use_context.rs

@@ -3,6 +3,7 @@ use dioxus_core::ScopeState;
 /// Consume some context in the tree, providing a sharable handle to the value
 ///
 /// Does not regenerate the value if the value is changed at the parent.
+#[must_use]
 pub fn use_context<T: 'static + Clone>(cx: &ScopeState) -> Option<&T> {
     cx.use_hook(|| cx.consume_context::<T>()).as_ref()
 }