aspnet/core/data/ef-mvc/ updates for 2.0

[Tratcher]

https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/

Signoff issue: aspnet/Release#176

Major item:
All the code around DbInitializer needs to be moved from Startup to Main. The old pattern is now causing problems with migrations.

        public static void Main(string[] args)
        {
            var host = BuildWebHost(args);
            
            using (var scope = host.Services.CreateScope())
            {
                var services = scope.ServiceProvider;
                try
                {
                    var context = services.GetRequiredService<SchoolContext>();
                    DbInitializer.Initialize(context);
                }
                catch (Exception ex)
                {
                    var logger = services.GetRequiredService<ILogger<Program>>();
                    logger.LogError(ex, "An error occurred while migrating the database.");
                }
            }
            
            host.Run();
        }

Standard cleanup:
Redo screenshots, update versions, redo command line sample output.

Minor items:

• Microsoft.EntityFrameworkCore.SqlServer no longer needs to be added, it's part of the metapackage.
• Create, Read, Update, and Delete operations: Edge won't let you enter invalid dates in a datetime-local field. You always get a date picker. Use a different validation example?
• Sorting, filtering, paging, and grouping: Why doesn't PaginatedList.cs have a namespace?

@bricelam
@Rick-Anderson adds - go thru entire series

[alexandr-osprey]

I've been struggling with error "LocalDb connection : Login failed" during migrations or any tries to connect to localdb. This really helped me. Such a treasonous problem.