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.

src/ol/events/Event.js

@@ -13,12 +13,10 @@
  * {@link module:ol/events/Target~Target}.
  */
 class BaseEvent {
-
   /**
    * @param {string} type Type.
    */
   constructor(type) {
-
     /**
      * @type {boolean}
      */
@@ -54,10 +52,8 @@ class BaseEvent {
   stopPropagation() {
     this.propagationStopped = true;
   }
-
 }
 
-
 /**
  * @param {Event|import("./Event.js").default} evt Event
  */
@@ -65,7 +61,6 @@ export function stopPropagation(evt) {
   evt.stopPropagation();
 }
 
-
 /**
  * @param {Event|import("./Event.js").default} evt Event
  */