Add logging for binary transparency atoms.

Added logging for vbmeta digest after devices boots.

Added logging for APEX Info after their SHA256 digests
are computed.

Bug: 214300670
Test: Build compiles and `statsd_testdrive` shows that
the atoms are recorded correctly and as expected.

Change-Id: I86d7ae8bdc8d7403943fda04a7ad9986b474abdf