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/easing.js

@@ -2,7 +2,6 @@
  * @module ol/easing
  */
 
-
 /**
  * Start slow and speed up.
  * @param {number} t Input between 0 and 1.
@@ -13,7 +12,6 @@ export function easeIn(t) {
   return Math.pow(t, 3);
 }
 
-
 /**
  * Start fast and slow down.
  * @param {number} t Input between 0 and 1.
@@ -24,7 +22,6 @@ export function easeOut(t) {
   return 1 - easeIn(1 - t);
 }
 
-
 /**
  * Start slow, speed up, and then slow down again.
  * @param {number} t Input between 0 and 1.
@@ -35,7 +32,6 @@ export function inAndOut(t) {
   return 3 * t * t - 2 * t * t * t;
 }
 
-
 /**
  * Maintain a constant speed over time.
  * @param {number} t Input between 0 and 1.
@@ -46,7 +42,6 @@ export function linear(t) {
   return t;
 }
 
-
 /**
  * Start slow, speed up, and at the very end slow down again.  This has the
  * same general behavior as {@link module:ol/easing~inAndOut}, but the final