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/heatmap-earthquakes.js

@@ -1,9 +1,9 @@
-import Map from '../src/ol/Map.js';
-import View from '../src/ol/View.js';
 import KML from '../src/ol/format/KML.js';
-import {Heatmap as HeatmapLayer, Tile as TileLayer} from '../src/ol/layer.js';
+import Map from '../src/ol/Map.js';
 import Stamen from '../src/ol/source/Stamen.js';
 import VectorSource from '../src/ol/source/Vector.js';
+import View from '../src/ol/View.js';
+import {Heatmap as HeatmapLayer, Tile as TileLayer} from '../src/ol/layer.js';
 
 const blur = document.getElementById('blur');
 const radius = document.getElementById('radius');
@@ -12,25 +12,25 @@ const vector = new HeatmapLayer({
   source: new VectorSource({
     url: 'data/kml/2012_Earthquakes_Mag5.kml',
     format: new KML({
-      extractStyles: false
-    })
+      extractStyles: false,
+    }),
   }),
   blur: parseInt(blur.value, 10),
   radius: parseInt(radius.value, 10),
-  weight: function(feature) {
+  weight: function (feature) {
     // 2012_Earthquakes_Mag5.kml stores the magnitude of each earthquake in a
     // standards-violating <magnitude> tag in each Placemark.  We extract it from
     // the Placemark's name instead.
     const name = feature.get('name');
     const magnitude = parseFloat(name.substr(2));
     return magnitude - 5;
-  }
+  },
 });
 
 const raster = new TileLayer({
   source: new Stamen({
-    layer: 'toner'
-  })
+    layer: 'toner',
+  }),
 });
 
 new Map({
@@ -38,17 +38,17 @@ new Map({
   target: 'map',
   view: new View({
     center: [0, 0],
-    zoom: 2
-  })
+    zoom: 2,
+  }),
 });
 
-const blurHandler = function() {
+const blurHandler = function () {
   vector.setBlur(parseInt(blur.value, 10));
 };
 blur.addEventListener('input', blurHandler);
 blur.addEventListener('change', blurHandler);
 
-const radiusHandler = function() {
+const radiusHandler = function () {
   vector.setRadius(parseInt(radius.value, 10));
 };
 radius.addEventListener('input', radiusHandler);