ArmVirtPkg: Add library for Arm CCA initialisation in PEI

Add ArmCcaInitPeiLib library that performs the Arm CCA specific
initialisation in the PEI phase like:
 - Configuring the system memory as Protected RAM.
 - Reading the Realm Config and storing the IPA width in
   a GUID HOB i.e., gArmCcaIpaWidthGuid for subsequent use.
 - Calling ArmCcaConfigureMmio () to configure the MMIO regions
   by setting the Unprotected IPA attribute in the page tables.

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