ArmPkg/MmCommunicationDxe: expose MM Communicate 2 protocol

ArmPkg/MmCommunicationDxe: expose MM Communicate 2 protocol

Implement the new MmCommunication2 protocol which supports the use
of standalone MM at runtime inside an address space that has been
virtually remapped by the OS.

Note that the implementation of the old MM Communicate protocol is
removed: it never worked correctly so there is no point in keeping it.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>