Show useSelector result in React DevTools

[Finesse]

Resolves #1525

I've checked the performance impact by calling useSelector 10000 times while rendering 1 component. Durations during mounts and updates:

	Before	After
React prod, browser console is closed	80ms, 45ms	81ms, 45ms
React dev, React DevTools are opened	100ms, 55ms	100ms, 55ms

The times vary a lot on each run so I've concluded that there is no noticeable performance difference and left the useDebugValue to be called regardless.

The benchmark code

<!--<script src="https://cdn.jsdelivr.net/npm/react@16.13.0/umd/react.production.min.js"></script>-->
<!--<script src="https://cdn.jsdelivr.net/npm/react-dom@16.13.0/umd/react-dom.production.min.js"></script>-->
<script src="https://cdn.jsdelivr.net/npm/react@16.13.0/umd/react.development.js"></script>
<script src="https://cdn.jsdelivr.net/npm/react-dom@16.13.0/umd/react-dom.development.js"></script>
<script src="https://cdn.jsdelivr.net/npm/redux@4.0.5/dist/redux.min.js"></script>
<script src="./react-redux.js"></script>

<div id="app"></div>
<script>
	var hookCallCount = 10000;

	var store = Redux.createStore(function(state) {
		return state || { foo: 'bar' };
	});

	function selector(state) {
		return state.foo;
	}

	function Component() {
		for (var i = 0; i < hookCallCount; ++i) {
			ReactRedux.useSelector(selector);
		}

		return 'Ok';
	}

	function App() {
		return React.createElement(
			ReactRedux.Provider,
			{ store: store },
			React.createElement(Component),
		);
	}

	console.time('First render');
	ReactDOM.render(
		React.createElement(App),
		document.getElementById('app'),
	);
	console.timeEnd('First render');

	setTimeout(() => {
		console.time('Update');
		ReactDOM.render(
			React.createElement(App),
			document.getElementById('app'),
		);
		console.timeEnd('Update');
	}, 1000);
</script>

Please consider that useDebugValue gives no effect with a React production bundle.

I haven't found a way to test a useDebugValue call therefore I haven't added a test. I will add if I know how.

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[Finesse]

It should be at the root of useSelector to make Redux DevTools show the value right besides the hook name

[timdorr]

LGTM. Thanks!