[rkp] Generalize CBOR conversion functions for reuse am: facc2b82cf am: 6b0c9acb3d am: e5db1963aa

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/2775150

Change-Id: Icd4666928ed78967cb83c47ce8acf2cd87113486
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>