Make code prettier

This updates ESLint and our shared eslint-config-openlayers to use Prettier.  Most formatting changes were automatically applied with this:

    npm run lint -- --fix

A few manual changes were required:

 * In `examples/offscreen-canvas.js`, the `//eslint-disable-line` comment needed to be moved to the appropriate line to disable the error about the `'worker-loader!./offscreen-canvas.worker.js'` import.
 * In `examples/webpack/exapmle-builder.js`, spaces could not be added after a couple `function`s for some reason.  While editing this, I reworked `ExampleBuilder` to be a class.
 * In `src/ol/format/WMSGetFeatureInfo.js`, the `// @ts-ignore` comment needed to be moved down one line so it applied to the `parsersNS` argument.

test/spec/util.js

@@ -1,16 +1,15 @@
-
 export function overrideRAF() {
   const raf = window.requestAnimationFrame;
   const caf = window.cancelAnimationFrame;
 
-  window.requestAnimationFrame = function(callback) {
+  window.requestAnimationFrame = function (callback) {
     return setTimeout(callback, 1);
   };
-  window.cancelAnimationFrame = function(key) {
+  window.cancelAnimationFrame = function (key) {
     return clearTimeout(key);
   };
 
-  return function() {
+  return function () {
     window.requestAnimationFrame = raf;
     window.cancelAnimationFrame = caf;
   };