Merge "Add add3prf.py and call it from get_rust_pky.py" am: bb90c3ad26 am: 5052c70dd8 am: b19e3646d3 am: 7306633e21

Original change: https://android-review.googlesource.com/c/platform/development/+/1451282

Change-Id: I213983db41347b6494024db1900f4f0ba64f0b91