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/geom/flat/flip.js

@@ -2,7 +2,6 @@
  * @module ol/geom/flat/flip
  */
 
-
 /**
  * @param {Array<number>} flatCoordinates Flat coordinates.
  * @param {number} offset Offset.
@@ -12,7 +11,14 @@
  * @param {number=} opt_destOffset Destination offset.
  * @return {Array<number>} Flat coordinates.
  */
-export function flipXY(flatCoordinates, offset, end, stride, opt_dest, opt_destOffset) {
+export function flipXY(
+  flatCoordinates,
+  offset,
+  end,
+  stride,
+  opt_dest,
+  opt_destOffset
+) {
   let dest, destOffset;
   if (opt_dest !== undefined) {
     dest = opt_dest;