metrics-ipmi-blobs: Convert to nanopb

Tested: Decoded a metric proto from a host and verified that the fields
all looked as expected and "normal" with decode successfully identifying
everything.

Change-Id: Iaa1b5500db6d1b93fae95d44a1045a858624cc51
Signed-off-by: William A. Kennington III <wak@google.com>
6 files changed