feat: add plugins including image-upload (#12)

This adds the image upload "plugin" and all the desired built-in plugins.
Per the following two tickets
https://openedx.atlassian.net/browse/TNL-9367
https://openedx.atlassian.net/browse/TNL-9475

I need to add the requisite plugins, as well as a framework for the image upload modal.

src/setupTest.js

@@ -6,6 +6,22 @@ import 'babel-polyfill';
 
 Enzyme.configure({ adapter: new Adapter() });
 
+/* need to mock window for tinymce on import, as it is JSDOM incompatible */
+
+Object.defineProperty(window, 'matchMedia', {
+  writable: true,
+  value: jest.fn().mockImplementation(query => ({
+    matches: false,
+    media: query,
+    onchange: null,
+    addListener: jest.fn(), // Deprecated
+    removeListener: jest.fn(), // Deprecated
+    addEventListener: jest.fn(),
+    removeEventListener: jest.fn(),
+    dispatchEvent: jest.fn(),
+  })),
+});
+
 // These configuration values are usually set in webpack's EnvironmentPlugin however
 // Jest does not use webpack so we need to set these so for testing
 process.env.ACCESS_TOKEN_COOKIE_NAME = 'edx-jwt-cookie-header-payload';