ART: APEX post-install check fsverity

Add a check that fsverity data is available and enabled for
updated artifacts.

Enable is not idempotent. So use a sequence of measure and
enable instead.

Bug: 125474642
Test: m
Test: manual
Change-Id: Ifceacf0ef0ac3625bacf1e5c33d59de9f6bde3d6