Implement Global Inventory Item

For redfish health, to identify the "Global" system
state, we needed something to associate against. This
is documented here:

https://github.com/openbmc/docs/blob/master/designs/redfish_health_rollup.md#chassis--system-health

And first used here:

https://github.com/openbmc/bmcweb/blob/4380545ee6b3985f30060e4828fe5ac3a1e3475e/redfish-core/lib/health.hpp#L171

Change-Id: I2d9f80a9a1108ab6c2c290217059865eb9820ebb
Signed-off-by: James Feist <james.feist@linux.intel.com>
1 file changed