Notebooks Gallery (#59)

* Initial commit

* Address PR comments

* Move notebook related stuff to NotebookManager and dynamically load it

* Add New gallery callout and other UI tweaks

* Update test snapshot

src/Explorer/Controls/CommandButton/CommandButtonComponent.tsx

@@ -15,15 +15,20 @@ import { ArcadiaMenuPickerProps } from "../Arcadia/ArcadiaMenuPicker";
  * Options for this component
  */
 export interface CommandButtonComponentProps {
+  /**
+   * font icon name for the button
+   */
+  iconName?: string;
+
   /**
    * image source for the button icon
    */
-  iconSrc: string;
+  iconSrc?: string;
 
   /**
    * image alt for accessibility
    */
-  iconAlt: string;
+  iconAlt?: string;
 
   /**
    * Click handler for command button click