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/Notebook/NotebookUtil.test.ts

@@ -43,10 +43,8 @@ const notebookRecord = makeNotebookRecord({
       source: 'display(HTML("<h1>Sample html</h1>"))',
       outputs: List.of({
         data: Object.freeze({
-          data: {
-            "text/html": "<h1>Sample output</h1>",
-            "text/plain": "<IPython.core.display.HTML object>"
-          }
+          "text/html": "<h1>Sample output</h1>",
+          "text/plain": "<IPython.core.display.HTML object>"
         } as MediaBundle),
         output_type: "display_data",
         metadata: undefined