Authorize GoogleMetis Redfish endpoints in Ecclesia and Milotic

Add the GoogleMetis ResourceEntity enum value, OEM CSDL schemas
(GoogleMetis_v1.xml and GoogleMetisCollection_v1.xml), generated
URI-to-entity mappings, and privilege registry entries to authorize
the custom Metis endpoints, which were introduced earlier.

Google-Bug-Id:465793367,465801830
PiperOrigin-RevId: 994556675
Change-Id: I908f45f13e328bb7c258345e02241ad1ab7517fc