Add ability to set group on new message files

[ietf-svn-bot]

owner:[email protected] type_enhancement | by [email protected]

---

Several different system users initiate message import (mailman, nobody(postfix)). Need a way to set the group id on new files.

---

Issue migrated from trac:2655 at 2022-03-03 10:56:03 +0000

[ietf-svn-bot]

@[email protected] changed status from new to under_review