chore: Clean up unused files, imports, and work on getting end-to-end tests and unit tests running (#2272)

docs/v2/extensions/modules/panel.md

@@ -0,0 +1,61 @@
+# Module: Panel
+
+An extension can register a Panel Module by defining a `getPanelModule` method.
+The panel module provides the ability to define `menuOptions` and `components`
+that can be used by the consuming application. `components` are React Components
+that can be displayed in the consuming application's "Panel" Component.
+
+![Panel Extension](../../assets/img/extensions-panel.gif)
+
+<center><i>A panel extension example</i></center>
+
+The `menuOptions`'s `target` key points to a registered `components`'s `id`. A
+`defaultContext` is applied to all `menuOption`s; however, each `menuOption` can
+optional provide it's own `context` value.
+
+The `getPanelModule` receives an object containing the `ExtensionManager`'s
+associated `ServicesManager` and `CommandsManager`.
+
+```js
+import MyComponent from './MyComponent.js';
+
+export default {
+  id: 'example-panel-module',
+
+  /**
+   * @param {object} params
+   * @param {ServicesManager} params.servicesManager
+   * @param {CommandsManager} params.commandsManager
+   */
+  getPanelModule({ servicesManager, commandsManager }) {
+    return {
+      menuOptions: [
+        {
+          // A suggested icon
+          // Available icons determined by consuming app
+          icon: 'list',
+          // A suggested label
+          label: 'Magic',
+          // 'right' or 'left'
+          from: 'right',
+          // The target component to toggle open/close
+          target: 'target-component-id',
+          // UI Hint; If the target panel is in a "disabled" state
+          isDisabled: studies => {
+            return false;
+          },
+          // Overrides `defaultContext`, if specified
+          context: ['ACTIVE_VIEWPORT:MAGIC'],
+        },
+      ],
+      components: [
+        {
+          id: 'target-component-id',
+          component: MyComponent,
+        },
+      ],
+      defaultContext: ['ROUTE:VIEWER'],
+    };
+  },
+};
+```