Remove subject id from the VC

Subject id must be represented in specific format, while currently it's arbitrarily contructed from policy group/name/version and causes problems with VC/VP signatures.

internal/credential/credentials.go

@@ -41,7 +41,7 @@ func (c *Credentials) NewCredential(contexts []string, subjectID string, subject
 		Issuer:  verifiable.Issuer{ID: c.issuerURI},
 		Issued:  &util.TimeWrapper{Time: time.Now()},
 		Subject: verifiable.Subject{
-			ID:           subjectID,
+			//ID:           subjectID,
 			CustomFields: subject,
 		},
 	}