Bootstrap ExamineX with IUmbracoBuilder extension methods instead of using IComposer

[Shazwazza]

To avoid any race conditions and to allow developers to have full control over when ExamineX maps Examine config to ExamineX config, ExamineX will now require explicit registration in Program.cs:

builder.CreateUmbracoBuilder()
    .AddBackOffice()
    .AddWebsite()
    .AddComposers()

    // Add ExamineX - must be after AddComposers!
    .AddExamineXAzureSearch()
    // If you are using the BlobMedia ExamineX feature
    //.AddExamineXForBlobMedia()
    // If you are using the Forms ExamineX feature
    //.AddExamineXForUmbracoForms()

    .Build();