Blazor CRUD scaffolder should add the EF Core migrations endpoint

[danroth27]

If you run the new Blazor CRUD scaffolder, it doesn't add the EF Core migrations endpoint, which makes it harder to run migrations to set up the database.

Repro steps:

• Create a new Blazor Web App with the default options
• Add a simple data mode
• Run the Blazor CRUD scaffolder
• Run the app and browser to the generated Index.razor page

Expected result: EF Core migrations endpoint renders a helpful error message saying you need to run migrations to set up the database.
Actual result: You get a difficult to understand error that EF Core couldn't connect to the database

Proposed fix:

• The scaffolder should add the Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore package, add a call to builder.Services.AddDatabaseDeveloperPageExceptionFilter(), and a call to app.UseMigrationsEndPoint() when in the Development environment.

[deepchoudhery]

sounds good, will aim for 8.0.1 timeline.