low: add hook support to scoped instances

[betula]

const scope_factory = () => {
  const v = value(0);
  hook(() => {
    const item = useExternalSelector(external_selector);
    v(item);
  });

return v;
};

const Child = () => {
  const val = useValue(useScoped(scope_factory));
  return (
    <span>{val}</span>
  )
}

const Root = () => {
  return (
    <ExternalContext>
      <Scope>
        <Child />
      </Scope>
    </ExternalContext>
  )
}

[betula]

Not possible in React context scope in contrast with local logic. Because local logic executed in React component who called factory. But in React context scope case, logic should be executed in the Scope component, not in the current execution context.