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/style/Image.js

@@ -3,7 +3,6 @@
  */
 import {abstract} from '../util.js';
 
-
 /**
  * @typedef {Object} Options
  * @property {number} opacity
@@ -13,7 +12,6 @@ import {abstract} from '../util.js';
  * @property {Array<number>} displacement
  */
 
-
 /**
  * @classdesc
  * A base class used for creating subclasses and not instantiated in
@@ -27,7 +25,6 @@ class ImageStyle {
    * @param {Options} options Options.
    */
   constructor(options) {
-
     /**
      * @private
      * @type {number}
@@ -57,7 +54,6 @@ class ImageStyle {
      * @type {Array<number>}
      */
     this.displacement_ = options.displacement;
-
   }
 
   /**
@@ -71,7 +67,7 @@ class ImageStyle {
       scale: this.getScale(),
       rotation: this.getRotation(),
       rotateWithView: this.getRotateWithView(),
-      displacement: this.getDisplacement().slice()
+      displacement: this.getDisplacement().slice(),
     });
   }