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/ImageCanvas.js

@@ -4,7 +4,6 @@
 import ImageBase from './ImageBase.js';
 import ImageState from './ImageState.js';
 
-
 /**
  * A function that is called to trigger asynchronous canvas drawing.  It is
  * called with a "done" callback that should be called when drawing is done.
@@ -14,9 +13,7 @@ import ImageState from './ImageState.js';
  * @typedef {function(function(Error=): void): void} Loader
  */
 
-
 class ImageCanvas extends ImageBase {
-
   /**
    * @param {import("./extent.js").Extent} extent Extent.
    * @param {number} resolution Resolution.
@@ -26,8 +23,8 @@ class ImageCanvas extends ImageBase {
    *     support asynchronous canvas drawing.
    */
   constructor(extent, resolution, pixelRatio, canvas, opt_loader) {
-
-    const state = opt_loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
+    const state =
+      opt_loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
 
     super(extent, resolution, pixelRatio, state);
 
@@ -49,7 +46,6 @@ class ImageCanvas extends ImageBase {
      * @type {?Error}
      */
     this.error_ = null;
-
   }
 
   /**
@@ -94,5 +90,4 @@ class ImageCanvas extends ImageBase {
   }
 }
 
-
 export default ImageCanvas;