ArmVirtualizationPkg: PlatformIntelBdsLib: add basic policy
    
    In PlatformBdsPolicyBehavior() we should follow the same pattern as in
    OvmfPkg's: after the consoles are connected,
    - connect all drivers and devices,
    - enumerate all boot options,
    - enter the Intel BDS FrontPage if the user presses a key different from
      Enter.
    
    We set the countdown to 3 seconds, similarly to the timeout that we
    specify for ARM BDS.
    
    Contributed-under: TianoCore Contribution Agreement 1.0
    Signed-off-by: Laszlo Ersek <lersek@redhat.com>