Fix HTML side content not working (#3310)

* Fix HTML Display runtime error

* Update test snapshot

Author: RichDom2185

src/commons/sideContent/__tests__/__snapshots__/SideContentHtmlDisplay.test.tsx.snap

@@ -5,7 +5,7 @@ exports[`HTML Display renders correctly 1`] = `
   className="sa-html-display"
   sandbox="allow-scripts"
   src="about:blank"
-  srcDoc="<p>Hello World!</p>"
+  srcDoc=""<p>Hello World!</p>""
   title="HTML Display"
 />
 `;

src/commons/sideContent/content/SideContentHtmlDisplay.tsx

@@ -47,7 +47,7 @@ const SideContentHtmlDisplayBase: React.FC<OwnProps & DispatchProps> = props =>
       className="sa-html-display"
       title="HTML Display"
       sandbox="allow-scripts"
-      srcDoc={JSON.parse(content)}
+      srcDoc={content}
       src="about:blank"
     />
   );