Adding Cypress for e2e testing (#85)

* using the higher-level react-testing-library, and regenerating snapshot - renders real DOM elements
* Basic e2e testing with Cypress, following the guide here: https://www.gatsbyjs.com/docs/how-to/testing/end-to-end-testing/ ; needed to install cypress-local to avoid jest-cypress collision
* Adding accessibility testing support and basic a11y tests
* adding failure logging
* Adding nightly test run
* Fix misc stuff from lighthouse (#81)
* Removing local-cypress, relying instead on a combination
of type reference and eslint-plugin-cypress;
adding cypress to jest ignore paths to avoid conflict -
`npm test` is now jest-only, use `npm run test:e2e` to run cypress tests
* updating comment to clarify timezone

client/cypress/plugins/index.js

@@ -0,0 +1,34 @@
+// / <reference types="cypress" />
+// ***********************************************************
+// This example plugins/index.js can be used to load plugins
+//
+// You can change the location of this file or turn off loading
+// the plugins file with the 'pluginsFile' configuration option.
+//
+// You can read more here:
+// https://on.cypress.io/plugins-guide
+// ***********************************************************
+
+// This function is called when a project is opened or re-opened (e.g. due to
+// the project's config changing)
+
+/**
+ * @type {Cypress.PluginConfig}
+ */
+// eslint-disable-next-line no-unused-vars
+module.exports = (on, config) => {
+  // `on` is used to hook into various events Cypress emits
+  // `config` is the resolved Cypress config
+  on('task', {
+    log(message) {
+      console.log(message);
+
+      return null;
+    },
+    table(message) {
+      console.table(message);
+
+      return null;
+    },
+  });
+};