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/draw-shapes.js

@@ -1,18 +1,21 @@
+import Draw, {
+  createBox,
+  createRegularPolygon,
+} from '../src/ol/interaction/Draw.js';
 import Map from '../src/ol/Map.js';
-import View from '../src/ol/View.js';
 import Polygon from '../src/ol/geom/Polygon.js';
-import Draw, {createRegularPolygon, createBox} from '../src/ol/interaction/Draw.js';
-import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
+import View from '../src/ol/View.js';
 import {OSM, Vector as VectorSource} from '../src/ol/source.js';
+import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
 
 const raster = new TileLayer({
-  source: new OSM()
+  source: new OSM(),
 });
 
 const source = new VectorSource({wrapX: false});
 
 const vector = new VectorLayer({
-  source: source
+  source: source,
 });
 
 const map = new Map({
@@ -20,8 +23,8 @@ const map = new Map({
   target: 'map',
   view: new View({
     center: [-11000000, 4600000],
-    zoom: 4
-  })
+    zoom: 4,
+  }),
 });
 
 const typeSelect = document.getElementById('type');
@@ -39,7 +42,7 @@ function addInteraction() {
       geometryFunction = createBox();
     } else if (value === 'Star') {
       value = 'Circle';
-      geometryFunction = function(coordinates, geometry) {
+      geometryFunction = function (coordinates, geometry) {
         const center = coordinates[0];
         const last = coordinates[1];
         const dx = center[0] - last[0];
@@ -49,7 +52,7 @@ function addInteraction() {
         const newCoordinates = [];
         const numPoints = 12;
         for (let i = 0; i < numPoints; ++i) {
-          const angle = rotation + i * 2 * Math.PI / numPoints;
+          const angle = rotation + (i * 2 * Math.PI) / numPoints;
           const fraction = i % 2 === 0 ? 1 : 0.5;
           const offsetX = radius * fraction * Math.cos(angle);
           const offsetY = radius * fraction * Math.sin(angle);
@@ -67,17 +70,16 @@ function addInteraction() {
     draw = new Draw({
       source: source,
       type: value,
-      geometryFunction: geometryFunction
+      geometryFunction: geometryFunction,
     });
     map.addInteraction(draw);
   }
 }
 
-
 /**
  * Handle change event.
  */
-typeSelect.onchange = function() {
+typeSelect.onchange = function () {
   map.removeInteraction(draw);
   addInteraction();
 };