add date and time formatting methods to localize service (#1616)

- uses Apple APIs for formatting on iOS
- uses .Net APIs for formatting Android
- implemented across project
- remove unnecesary calls to DateTimeConverter

src/App/Abstractions/ILocalizeService.cs

@@ -1,9 +1,22 @@
-using System.Globalization;
+using System;
+using System.Globalization;
 
 namespace Bit.App.Abstractions
 {
     public interface ILocalizeService
     {
         CultureInfo GetCurrentCultureInfo();
+
+        /// <summary>
+        /// Format date using device locale.
+        /// Needed for iOS as it provides locales unsupported in .Net
+        /// </summary>
+        string GetLocaleShortDate(DateTime? date);
+
+        /// <summary>
+        /// Format time using device locale.
+        /// Needed for iOS as it provides locales unsupported in .Net
+        /// </summary>
+        string GetLocaleShortTime(DateTime? time);
     }
 }