Stylesheets: Take advantage of Font stacking (#5111)

Depends on https://github.com/space-wizards/RobustToolbox/pull/2182
 - Adds Noto Sans Symbols and its sequel, Noto Sans Symbols 2: Revenge
   of the Unicode.
 - Uses a stack of Noto Sans, Symbols, and Symbols 2 in all places where
   Noto Sans/Noto Sans Display are used.

If you _really_ wanted to, you could use this to add Noto Emoji too.

In considering this, please remember that not everything that _can_ be
done, _should_ be done.

Content.Client/Resources/ResourceCacheExtensions.cs

@@ -27,5 +27,23 @@ namespace Content.Client.Resources
         {
             return cache.GetFont(new ResourcePath(path), size);
         }
+
+        public static Font GetFont(this IResourceCache cache, ResourcePath[] path, int size)
+        {
+            var fs = new Font[path.Length];
+            for (var i = 0; i < path.Length; i++)
+                fs[i] = new VectorFont(cache.GetResource<FontResource>(path[i]), size);
+
+            return new StackedFont(fs);
+        }
+
+        public static Font GetFont(this IResourceCache cache, string[] path, int size)
+        {
+            var rp = new ResourcePath[path.Length];
+            for (var i = 0; i < path.Length; i++)
+                rp[i] = new ResourcePath(path[i]);
+
+            return cache.GetFont(rp, size);
+        }
     }
 }