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>
diff --git a/.gitignore b/.gitignore
index 4691b58..c21db72 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@
 !subprojects/nemora-postd/
 !subprojects/bare-metal-host-monitor/
 !subprojects/googletest.wrap
+!subprojects/nanopb.wrap
 !subprojects/phosphor-dbus-interfaces.wrap
 !subprojects/phosphor-logging.wrap
 !subprojects/sdbusplus.wrap