update: New Hooks API

[idreyn]

This PR updates the way reactive attributes access hooks like useState and useEffect. Previously, these values were bound to this in an attribute hook:

function useTicker(this: Hooks) {
	const { useState, useEffect } = this;
	const [ticks, setTicks] = useState(0);

	useEffect(() => {
		const interval = setInterval(() => setTicks((t) => t + 1), 1000);
		return () => clearInterval(interval);
	}, []);

	return ticks;
}

Because TypeScript forces you to annotate this as an argument to the function, this is more confusing than it is slick. It also forces you to use the function keyword to define your hook functions, which, eh. This change introduces global versions of hook primitives that are exported from the package, which are used as follows:

import { useState, useEffect } from '@pubpub/prosemirror-reactive';

const useTicker = () => {
	const [ticks, setTicks] = useState(0);

	useEffect(() => {
		const interval = setInterval(() => setTicks((t) => t + 1), 1000);
		return () => clearInterval(interval);
	}, []);

	return ticks;
}

This matches the React API and reduces the number of things you have to know to write a valid attribute hook.