Further improve colorization of embeded expressions

- Add groovy embedded support
- Make high contrast colorization consistent

extensions/theme-defaults/themes/dark_vs.json

@@ -10,7 +10,7 @@
 			}
 		},
 		{
-			"scope": "meta.embedded",
+			"scope": ["meta.embedded", "source.groovy.embedded"],
 			"settings": {
 				"foreground": "#D4D4D4",
 				"background": "#1E1E1E"