Add JWT, OTP, and caching features

Upgraded projects to .NET 9.0 and added new projects `KBR.Cache`, `KBR.Shared`, and `KBR.Shared.Lite` to the solution. Introduced JWT authentication and OTP handling with new models, services, and configuration options. Updated database schema with new entities `Users` and `RefreshTokens`, and added migrations for schema changes. Implemented caching strategies using `AppDistributedCache` with support for in-memory, SQL Server, and Redis. Enhanced email handling with `MailHelpers` for domain replacement. Updated controllers, repositories, and configuration files to support new features.

Shared/KBR.Shared/Cache/CacheExtensions.cs

@@ -0,0 +1,28 @@
+using KBR.Shared.Lite.Extensions;
+
+namespace KBR.Shared.Cache
+{
+    public static class CacheExtensions
+    {
+        public static byte[] ToByteArray(this object obj)
+        {
+            if (obj is not null)
+            {
+                return JsonExtensions.ToUtf8Bytes(obj);
+            }
+
+            return Array.Empty<byte>();
+        }
+
+        public static T? FromByteArray<T>(this byte[] byteArray)
+            where T : class
+        {
+            if (byteArray is null)
+            {
+                return default;
+            }
+
+            return JsonExtensions.ToObject<T>(byteArray);
+        }
+    }
+}