Add LanguageSwitcher component

Oqtane.Server/Startup.cs

@@ -127,6 +127,7 @@ namespace Oqtane
             services.AddScoped<ISiteTemplateService, SiteTemplateService>();
             services.AddScoped<ISqlService, SqlService>();
             services.AddScoped<ISystemService, SystemService>();
+            services.AddScoped<ILocalizationService, LocalizationService>();
 
             services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();