ArmVirtPkg/PlatformBootManagerLib: display boot option loading/starting
    
    Consume PlatformBmPrintScLib, added earlier in this series. When
    BdsDxe+UefiBootManagerLib report LoadImage() / StartImage() preparations
    and return statuses, print the reports to the UEFI console. This allows
    end-users better visibility into the boot process.
    
    Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1515418
    Contributed-under: TianoCore Contribution Agreement 1.1
    Signed-off-by: Laszlo Ersek <lersek@redhat.com>