Add instructions for in-mem DB and show SQL output

[Rick-Anderson]

Update StartupSQLite with the following code.

public void ConfigureServices(IServiceCollection services)
{
    services.AddRazorPages();

#if !IN_MEM
    services.AddDbContext<SchoolContext>(options =>
            options.UseSqlite(Configuration.GetConnectionString("SchoolContext")));
#else

    services.AddDbContext<SchoolContext>(options =>
options.UseInMemoryDatabase("InMemorySchoolContext"));
#endif

    services.AddDatabaseDeveloperPageExceptionFilter();
}

Doesn't work with concurrency, see dotnet/efcore#10625

Also add section on showing SQL output. See https://stackoverflow.com/a/66662556/502537

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Document Details

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• ID: 7a54c97f-ddd4-b041-5e5f-a2df009ace50
• Version Independent ID: fa488196-1f98-08ea-adcc-17d9dac86727
• Content: Razor Pages with Entity Framework Core in ASP.NET Core - Tutorial 1 of 8
• Content Source: aspnetcore/data/ef-rp/intro.md
• Product: aspnet-core
• Technology: aspnetcore-data
• GitHub Login: @Rick-Anderson
• Microsoft Alias: riande