PM-3350 Fix Avatar toolbar icon on extensions to load properly and to take advantage of using directly SkiaSharp to do the native conversion to UIImage. Also improved the toolbar item so that size is set appropriately.

src/Core/Controls/Avatar/AvatarImageSourcePool.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Concurrent;
+
+namespace Bit.App.Controls
+{
+    public interface IAvatarImageSourcePool
+    {
+        AvatarImageSource GetOrCreateAvatar(string userId, string name, string email, string color);
+    }
+
+    public class AvatarImageSourcePool : IAvatarImageSourcePool
+    {
+        private readonly ConcurrentDictionary<string, AvatarImageSource> _cache = new ConcurrentDictionary<string, AvatarImageSource>();
+
+        public AvatarImageSource GetOrCreateAvatar(string userId, string name, string email, string color)
+        {
+            var key = $"{userId}{name}{email}{color}";
+            if (!_cache.TryGetValue(key, out var avatar))
+            {
+                avatar = new AvatarImageSource(userId, name, email, color);
+                if (!_cache.TryAdd(key, avatar)
+                    &&
+                    !_cache.TryGetValue(key, out avatar)) // If add fails another thread created the avatar in between the first try get and the try add.
+                {
+                    // if add and get after fails, then something wrong is going on with this method.
+                    throw new InvalidOperationException("Something is wrong creating the avatar image");
+                }
+            }
+            return avatar;
+        }
+    }
+}
+