ArmVirtPkg: add FDF rule for self-relocating PrePi

ArmVirtPkg: add FDF rule for self-relocating PrePi

In preparation for making the self-relocating PrePi use the ordinary
BasePeCoffLib routines for relocating the image in place in memory
at start, add a special FDF rule that builds SEC modules as PE32
images with the relocation metadata preserved.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Sami Mujawar <Sami.Mujawar@arm.com>