Began transition to Vue3.

Implemented logging in and logging out.

Implemented authenticated http client.

Laid some groundwork for SCSS.

MultiShop/client/tests/e2e/specs/app.spec.js

@@ -0,0 +1,8 @@
+const App = require('../pageobjects/app.page')
+
+describe('Vue.js app', () => {
+  it('should open and render', () => {
+    App.open()
+    expect(App.heading).toHaveText('Welcome to Your Vue.js App')
+  })
+})