Add system/extras/verity/build_verity_metadata.py  to otatools am: d26a99c3c6 am: 1e7c1290c6 am: b25a7f38a8
am: b637cb2e99

* commit 'b637cb2e996febbab295b83af8176ec39b864186':
  Add system/extras/verity/build_verity_metadata.py  to otatools

Change-Id: Id9010ec71abb8f7db351914e2f99eec5e62f6f81