operations: Do not resolve revision for zero oid

In most of the operations RPCs we are verifying the expectedOldOID. And in the documentation of those RPCs it says "If set, it must either contain a valid, full object ID or the zero object ID in case the branch should be created. Otherwise, this RPC will return an error.". But actually these RPCs will return error for the zero object ID as well because of how git-rev-parse(1) works. It tries to verify an existing object when ^{object} type peeling operator appended to the object id. For zero OIDs we should simply skip the ResolveRevision call.

Closes #6290