Added support for acknowledging code of conduct for using public Notebook Gallery (#117)

* minro code edits

* Added support for acknowledging code of conduct

- Added CodeOfConduct component that shows links and a checkbox that must be acknwledged before seeing the public galley
- Added verbose message for notebook publish error (when another notebook with the same name exists in the gallery)
- Added a feature flag for enabling code of conduct acknowledgement

* Added Info Component

* minor edit

* fixed failign tests

* publish tab displayed only when code of conduct accepted

* added code of conduct fetch during publish

* fixed bug

* added test and addressed PR comments

* changed line endings

* added comment

* addressed PR comments

src/Explorer/Controls/NotebookGallery/InfoComponent/InfoComponent.test.tsx

@@ -0,0 +1,10 @@
+import { shallow } from "enzyme";
+import React from "react";
+import { InfoComponent } from "./InfoComponent";
+
+describe("InfoComponent", () => {
+  it("renders", () => {
+    const wrapper = shallow(<InfoComponent />);
+    expect(wrapper).toMatchSnapshot();
+  });
+});