refactor(HomeController): remove culture binding as viewdata; bind via string localizer

EnvelopeGenerator.Web/Program.cs

@@ -90,7 +90,7 @@ try
 
     //AddEF Core dbcontext
     var useDbMigration = Environment.GetEnvironmentVariable("MIGRATION_TEST_MODE") == true.ToString() || config.GetValue<bool>("UseDbMigration");
-    var cnnStrName = useDbMigration ? Key.DbMigrationTest : Key.Default;
+    var cnnStrName = useDbMigration ? "DbMigrationTest" : "Default";
     var connStr = config.GetConnectionString(cnnStrName)
         ?? throw new InvalidOperationException($"Connection string '{cnnStrName}' is missing in the application configuration.");