Use driver pattern for e2e tests (#829)

I've moved all the logic relevant to WBIO into a single file in order to
be able to replace it.
I have tried to upgrade WDIO in order to use the latest version and it
got stuck on my computer.
Furthermore, I was not able to run it locally which made this whole
cycle very long.
After this will be merged I will replace WDIO with cypress.
This doesn't change anything, only moves some code in the tests to a
single file, removes unneeded files and uses the driver pattern, which
will later allow switching the underline WDIO with Cypress.

cc: @nyurik

test/functional/util/webdriverio-ext.js

@@ -1,63 +0,0 @@
-var artifacts = require("../../artifacts");
-var path = require("path");
-
-const extendWebdriverIO = async function() {
-  await browser.setTimeout({ 'script': 20 * 1000 });
-  await browser.setTimeout({ 'implicit': 20 * 1000 });
-
-  var SCREENSHOTS_PATH = artifacts.pathSync("/screenshots");
-
-  /**
-   * Sometimes chrome driver can result in the wrong text.
-   *
-   * See <https://github.com/webdriverio/webdriverio/issues/1886>
-   */
-  try {
-    await browser.addCommand('setValueSafe', async function (selector, text) {
-      for (var i = 0; i < 10; i++) {
-        const elem = await $(selector);
-        await elem.waitForDisplayed(500);
-
-        var elements = await browser.findElements("css selector", selector);
-        if (elements.length > 1) {
-          throw "Too many elements found";
-        }
-
-        const elem2 = await $(selector);
-        await elem2.setValue(text);
-
-        var browserText = await elem2.getValue();
-
-        if (browserText == text) {
-          return;
-        }
-        else {
-          console.error("Warning: setValue failed, trying again");
-        }
-      }
-
-      // Wait for change events to fire and state updated
-      await browser.flushReactUpdates();
-    })
-
-    await browser.addCommand('takeScreenShot', async function (filepath) {
-      var savepath = path.join(SCREENSHOTS_PATH, filepath);
-      await browser.saveScreenshot(savepath);
-    });
-
-    await browser.addCommand('flushReactUpdates', async function () {
-      await browser.executeAsync(function (done) {
-        // For any events to propagate
-        setTimeout(function () {
-          // For the DOM to be updated.
-          setTimeout(done, 0);
-        }, 0)
-      })
-    })
-
-  } catch (err) {
-    console.error(">>> Ignored error: " + err);
-  }
-}
-
-module.exports = extendWebdriverIO;