Move inherits keyword from errors.yaml to metadata.yaml

The metadata.yaml file is the correct location for the inherits.
Update the elog-gen.py parser to support this change.

Change-Id: Iac7f67ec72e761ab3dafbf89c7e4d5495b34f00d
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/tools/example/xyz/openbmc_project/Example/Elog.metadata.yaml b/tools/example/xyz/openbmc_project/Example/Elog.metadata.yaml
index 244127c..f0838e0 100644
--- a/tools/example/xyz/openbmc_project/Example/Elog.metadata.yaml
+++ b/tools/example/xyz/openbmc_project/Example/Elog.metadata.yaml
@@ -7,6 +7,8 @@
       type: string
     - str: FILE_NAME=%s
       type: string
+  inherits:
+    - TestErrorTwo
 
 - name: TestErrorTwo
   level: ERR