[rkp] Generalize CBOR conversion functions for reuse am: facc2b82cf am: 6b0c9acb3d am: e5db1963aa am: 69b89f3e51

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

Change-Id: I680a8b36cf656a8343a1a7f552beb18309967298
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>