js-tools: Add missing eslint plugin dep (#21642)

Eslint "sharable configs" are supposed to peer-depend on any plugins
they need. But people usually forget this because npm hoisting makes it
usually work anyway.

In this case, eslint-config-wpcalypso was missing a peer dep on
eslint-plugin-react-hooks.

This happened to work before because eslint-changed was shelling out to
eslint, which runs from `node_modules/.pnpm/eslint@7.32.0/node_modules/eslint`,
which was picking up the dep from `node_modules/.pnpm/node_modules` that
even pnpm puts in place to handle crap like this.

When #21606 switched eslint-changed to use eslint's API instead of
shelling out, it doesn't run from within `node_modules/.pnpm/` anymore
(because eslint-changed is in the monorepo), so
`node_modules/.pnpm/node_modules` is no longer in node's path, so it no
longer would find the plugin.

The solution is to add the missing plugin to js-tools's deps, because
`tools/js-tools/node_modules` will still be in the path with the way we
have things set up.

tools/js-tools/package.json

@@ -28,6 +28,7 @@
 		"eslint-plugin-lodash": "7.3.0",
 		"eslint-plugin-prettier": "3.4.1",
 		"eslint-plugin-react": "7.26.1",
+		"eslint-plugin-react-hooks": "4.2.0",
 		"eslint-plugin-wpcalypso": "5.0.0",
 		"glob": "7.1.6",
 		"ignore": "5.1.8",