StoreProvider widget that can inject the store into the vdom tree

[agubler]

Enhancement

Add a new module StoreProvider that can be used like any widget within the widget tree, and will inject a store into a renderer function so that state and processes can be passed as properties.

interface State {
	foo: string;
	bar: {
		baz: string;
	}
}

class MyApp extends WidgetBase {
	protected render() {
		return w(StoreProvider, { stateKey: 'state', (store: Store<State>) => {
			return v('div', [ store.get(store.path('foo')) ]);
		}})
	}
}

This will replace the existing StoreContainer in a major release after 4.0.0 and the migration guide and upgrade tool warn that usages of StoreContainer should be converted to use StoreProvider.