[EC-1002] [BEEEP] Add ability to change language in app (#2299)

* EC-1002 BEEEP Added ability to change language in app

* EC-1002 fix format

* EC-1002 Renamed IPreferencesStorageService to ISynchronousStorageService

* EC-1002 Moved get/set Locale to the StateService and added the StorageMediatorService to a new way to interact with the storage. Later the StateService will only interact with this mediator instead of directly with the storage services, with this we have more control inside the mediator and we can have both sync and async methods to interact with storages handled by the mediator

src/Core/Abstractions/II18nService.cs

@@ -9,6 +9,7 @@ namespace Bit.Core.Abstractions
         CultureInfo Culture { get; set; }
         StringComparer StringComparer { get; }
         Dictionary<string, string> LocaleNames { get; }
+        void SetCurrentCulture(CultureInfo culture);
         string T(string id, string p1 = null, string p2 = null, string p3 = null);
         string Translate(string id, string p1 = null, string p2 = null, string p3 = null);
     }

src/Core/Abstractions/IStateService.cs

@@ -6,6 +6,7 @@ using Bit.Core.Models.Data;
 using Bit.Core.Models.Domain;
 using Bit.Core.Models.Response;
 using Bit.Core.Models.View;
+using Bit.Core.Services;
 
 namespace Bit.Core.Abstractions
 {
@@ -165,5 +166,7 @@ namespace Bit.Core.Abstractions
         Task<string> GetAvatarColorAsync(string userId = null);
         Task<string> GetPreLoginEmailAsync();
         Task SetPreLoginEmailAsync(string value);
+        string GetLocale();
+        void SetLocale(string locale);
     }
 }

src/Core/Abstractions/IStorageMediatorService.cs

@@ -0,0 +1,16 @@
+using System.Threading.Tasks;
+using Bit.Core.Services;
+
+namespace Bit.Core.Abstractions
+{
+    public interface IStorageMediatorService
+    {
+        T Get<T>(string key);
+        void Save<T>(string key, T obj);
+        void Remove(string key);
+
+        Task<T> GetAsync<T>(string key, StorageMediatorOptions options = default);
+        Task SaveAsync<T>(string key, T obj, StorageMediatorOptions options = default);
+        Task RemoveAsync(string key, StorageMediatorOptions options = default);
+    }
+}

src/Core/Abstractions/ISynchronousStorageService.cs

@@ -0,0 +1,9 @@
+namespace Bit.Core.Abstractions
+{
+    public interface ISynchronousStorageService
+    {
+        T Get<T>(string key);
+        void Save<T>(string key, T obj);
+        void Remove(string key);
+    }
+}