ArmVirtPkg: Introduce Realm Aperture Management Protocol

The Realm Aperture Management Protocol (RAMP) is used to manage
the sharing of buffers between the Guest and Host. It configures
the memory regions as Protected EMPTY or Protected RAM by calling
RSI_IPA_STATE_SET command. The RAMP provides interfaces that device
drivers can use to open/close apertures for sharing buffers.

The RAMP also keeps track of the apertures that have been opened
and closes them on ExitBootServices. It also registers for reset
notification and closes all open apertures before the platform
resets the system.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>