arm: Add a library to verify tokens using the QCBOR library

Add a library wrapper around the QCBOR for parsing the Arm CCA attestation
tokens.

Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>