Add 0BSD support to add3prf.py

This adds the ability to detect and generate the correct METADATA file
for 0BSD licensed crates.

Bug: 317214883
Test: atest --host add3prf_test; Ran against https://crates.io/crates/adler
Change-Id: I064297212dbbcf7f195cde5e0b345f43da9369df
2 files changed