[iOS] Duplicate //components/safe_browsing_db/util

This is temporary code duplication to remove dependency
of iOS on safe_browsing_db.

BUG=543161
TBR=agl

Review URL: https://codereview.chromium.org/1571783002

Cr-Commit-Position: refs/heads/master@{#368366}
12 files changed