metadata: add interface to build associations
metadata: add interface to build associations

A metadata field found in the journal corresponding to an error could be
special in the sense that it may require building specific error
association objects. Add an interface to build such associations.

Take advantage of the fact that every metadata has a corresponding type
defined.

Change-Id: I09e446879667044c009141443fc0dc6fed8a8b18
Signed-off-by: Deepak Kodihalli <54105a30055f1e07853b8ee7a2f0d75d22ed98c1@in.ibm.com>

openbmc/phosphor-logging,openbmc/phosphor-logging,openbmc/phosphor-logging,openbmc/phosphor-logging