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/ImageTile.js

@@ -6,9 +6,7 @@ import TileState from './TileState.js';
 import {createCanvasContext2D} from './dom.js';
 import {listenImage} from './Image.js';
 
-
 class ImageTile extends Tile {
-
   /**
    * @param {import("./tilecoord.js").TileCoord} tileCoord Tile coordinate.
    * @param {TileState} state State.
@@ -17,8 +15,14 @@ class ImageTile extends Tile {
    * @param {import("./Tile.js").LoadFunction} tileLoadFunction Tile load function.
    * @param {import("./Tile.js").Options=} opt_options Tile options.
    */
-  constructor(tileCoord, state, src, crossOrigin, tileLoadFunction, opt_options) {
-
+  constructor(
+    tileCoord,
+    state,
+    src,
+    crossOrigin,
+    tileLoadFunction,
+    opt_options
+  ) {
     super(tileCoord, state, opt_options);
 
     /**
@@ -55,7 +59,6 @@ class ImageTile extends Tile {
      * @type {import("./Tile.js").LoadFunction}
      */
     this.tileLoadFunction_ = tileLoadFunction;
-
   }
 
   /**
@@ -139,7 +142,6 @@ class ImageTile extends Tile {
   }
 }
 
-
 /**
  * Get a 1-pixel blank image.
  * @return {HTMLCanvasElement} Blank image.