Add script to install vendor snapshot

This script installs Android.bp under prebuilts/vendor/v{version}. This
script only supports basic operations, so artifacts from "m dist
vendor-snapshot" must be unzipped under the directory before running
this script; features including automatic un-zipping, fetching artifacts
from server, etc. are to be supported in later versions.

Bug: 65377115
Test: m dist vendor-snapshot && run update.py
Change-Id: I1e0ae6a7d2b9bc991694943bd44b84a0dc3c9f30
2 files changed