Added Backstage logo to the Open Graph Image metadata of backstage.io (#2401)

* updated svg to png

* updated spaces with hex values

* removed spaces from filenames

* added deleted files

microsite/siteConfig.js

@@ -93,8 +93,10 @@ const siteConfig = {
   cleanUrl: true,
 
   // Open Graph and Twitter card images.
-  ogImage: 'img/logo-gradient-on-dark.svg',
-  twitterImage: 'img/logo-gradient-on-dark.svg',
+  ogImage:
+    'logo_assets/png/Backstage_Identity_Assets_Artwork_RGB_04_Icon_Teal.png',
+  twitterImage:
+    'logo_assets/png/Backstage_Identity_Assets_Artwork_RGB_04_Icon_Teal.png',
 
   // For sites with a sizable amount of content, set collapsible to true.
   // Expand/collapse the links and subcategories under categories.