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.

examples/xyz.js

@@ -1,21 +1,21 @@
 import Map from '../src/ol/Map.js';
-import View from '../src/ol/View.js';
 import TileLayer from '../src/ol/layer/Tile.js';
+import View from '../src/ol/View.js';
 import XYZ from '../src/ol/source/XYZ.js';
 
-
 const map = new Map({
   target: 'map',
   layers: [
     new TileLayer({
       source: new XYZ({
-        url: 'https://{a-c}.tile.thunderforest.com/cycle/{z}/{x}/{y}.png' +
-            '?apikey=0e6fc415256d4fbb9b5166a718591d71'
-      })
-    })
+        url:
+          'https://{a-c}.tile.thunderforest.com/cycle/{z}/{x}/{y}.png' +
+          '?apikey=0e6fc415256d4fbb9b5166a718591d71',
+      }),
+    }),
   ],
   view: new View({
     center: [-472202, 7530279],
-    zoom: 12
-  })
+    zoom: 12,
+  }),
 });