Fix bug publish screenshot (#762)

[Preview this branch](https://cosmos-explorer-preview.azurewebsites.net/pull/762?feature.someFeatureFlagYouMightNeed=true)

The main change in this PR fixes the snapshot functionality in the Publish pane-related components. Because the code cell outputs are now rendered in their own iframes for security reasons, a single snapshot of the notebook is no longer possible: each cell output takes its own snapshot and the snapshots are collated on the main notebook snapshot.
- Move the snapshot functionality to notebook components: this removes the reference of the notebook DOM node that we must pass to the Publish pane via explorer.
- Add slice in the state and actions in notebook redux for notebook snapshot requests and result
- Add post robot message to take snapshots and receive results
- Add logic in `NotebookRenderer` to wait for all output snapshots done before taking the main one collating.
- Use `zustand` to share snapshot between Redux world and React world. This solves the issue of keeping the `PanelContainer` component generic, while being able to update its children (`PublishPanel` component) with the new snapshot.

Additional changes:
- Add `local()` in `@font-face` to check if font is already installed before downloading the font (must be done for Safari, but not Edge/Chrome)
- Add "Export output to image" menu item in notebook cell, since each cell output can take its own snapshot (which can be downloaded)
![image](https://user-images.githubusercontent.com/21954022/117454706-b5f16600-af46-11eb-8535-6bf99f3d9170.png)

src/Explorer/Panes/PublishNotebookPane/PublishNotebookPane.test.tsx

@@ -12,13 +12,14 @@ describe("PublishNotebookPaneComponent", () => {
       notebookAuthor: "CosmosDB",
       notebookCreatedDate: "2020-07-17T00:00:00Z",
       notebookObject: undefined,
-      notebookParentDomElement: undefined,
+      notebookContentRef: undefined,
       setNotebookName: undefined,
       setNotebookDescription: undefined,
       setNotebookTags: undefined,
       setImageSrc: undefined,
       onError: undefined,
       clearFormError: undefined,
+      onTakeSnapshot: undefined,
     };
 
     const wrapper = shallow(<PublishNotebookPaneComponent {...props} />);