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/layer/Image.js

@@ -4,7 +4,6 @@
 import BaseImageLayer from './BaseImage.js';
 import CanvasImageLayerRenderer from '../renderer/canvas/ImageLayer.js';
 
-
 /**
  * @classdesc
  * Server-rendered images that are available for arbitrary extents and
@@ -16,7 +15,6 @@ import CanvasImageLayerRenderer from '../renderer/canvas/ImageLayer.js';
  * @api
  */
 class ImageLayer extends BaseImageLayer {
-
   /**
    * @param {import("./BaseImage.js").Options=} opt_options Layer options.
    */
@@ -32,7 +30,6 @@ class ImageLayer extends BaseImageLayer {
   createRenderer() {
     return new CanvasImageLayerRenderer(this);
   }
-
 }
 
 export default ImageLayer;