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

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

Change-Id: I2a7881b7d118aad1729091cb87fc438581116779
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>