Move Sample app connection string to configuration file (#621)

Author: mpreyskurantov

net/Sample/Program.cs

@@ -20,7 +20,7 @@ public static void Main(string[] args) {
                 .AddEntityFrameworkSqlServer()
                 .AddDbContext<NorthwindContext>(options => options
                     //.UseSqlServer("Server=.\\SQLEXPRESS; Database=Northwind; Trusted_Connection=True")
-                    .UseSqlServer("Data Source=(localdb)\\MSSQLLocalDB; Database=Northwind; Integrated Security=True; MultipleActiveResultSets=True; App=EntityFramework")
+                    .UseSqlServer(builder.Configuration.GetConnectionString("NorthwindConnectionString"))
                 );
 
             var app = builder.Build();

net/Sample/appsettings.json

@@ -0,0 +1,6 @@
+{
+  "ConnectionStrings": {
+    "NorthwindConnectionString": "Data Source=(localdb)\\MSSQLLocalDB; Database=Northwind; Integrated Security=True; MultipleActiveResultSets=True; App=EntityFramework",
+    "NorthwindConnectionStringIis": "Data Source=.; Database=Northwind; User Id=; Password=; MultipleActiveResultSets=True; App=EntityFramework; TrustServerCertificate=True"
+  }
+}