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/format/GML.js

@@ -15,7 +15,6 @@ import GML3 from './GML3.js';
  */
 const GML = GML3;
 
-
 /**
  * Encode an array of features in GML 3.1.1 Simple Features.
  *
@@ -27,7 +26,6 @@ const GML = GML3;
  */
 GML.prototype.writeFeatures;
 
-
 /**
  * Encode an array of features in the GML 3.1.1 format as an XML node.
  *