Fix Clipboard clear after time on iOS (#1679)

* Fixed Clipboard clear after x seconds depending on what the user set. Also refactored a bit to make the Clipboard a custom service to provide a better way to handle this situation #1464

* Clear some usings #1464

src/Core/Abstractions/IClipboardService.cs

@@ -0,0 +1,16 @@
+using System.Threading.Tasks;
+
+namespace Bit.Core.Abstractions
+{
+    public interface IClipboardService
+    {
+        /// <summary>
+        /// Copies the <paramref name="text"/> to the Clipboard.
+        /// If <paramref name="expiresInMs"/> is set > 0 then the Clipboard will be cleared after this time in milliseconds.
+        /// if less than 0 then it takes the configuration that the user set in Options.
+        /// </summary>
+        /// <param name="text">Text to be copied to the Clipboard</param>
+        /// <param name="expiresInMs">Expiration time in milliseconds of the copied text</param>
+        Task CopyTextAsync(string text, int expiresInMs = -1);
+    }
+}