Generate RaftGroupId from OMServiceID

Ratis requires RaftGroupId to be a UUID. We need to generate this ID from the OMServiceID so that it is consistent across all the OM nodes in a HA service.

Currently, we expect OMServiceId to be a 16 character string so that it can be converted to a UUID. But OMServiceID is a user configurable setting. Hence we cannot force users to input a 16 character string.

One option is to hash the OMServiceID string then truncate to UUID length and use that to generate the UUID.