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/Fill.js

@@ -2,7 +2,6 @@
  * @module ol/style/Fill
  */
 
-
 /**
  * @typedef {Object} Options
  * @property {import("../color.js").Color|import("../colorlike.js").ColorLike} [color=null] A color, gradient or pattern.
@@ -10,7 +9,6 @@
  * Default null; if null, the Canvas/renderer default black will be used.
  */
 
-
 /**
  * @classdesc
  * Set fill style for vector features.
@@ -21,7 +19,6 @@ class Fill {
    * @param {Options=} opt_options Options.
    */
   constructor(opt_options) {
-
     const options = opt_options || {};
 
     /**
@@ -39,7 +36,7 @@ class Fill {
   clone() {
     const color = this.getColor();
     return new Fill({
-      color: Array.isArray(color) ? color.slice() : color || undefined
+      color: Array.isArray(color) ? color.slice() : color || undefined,
     });
   }
 
@@ -61,7 +58,6 @@ class Fill {
   setColor(color) {
     this.color_ = color;
   }
-
 }
 
 export default Fill;