Add field group_name or something similar

[rkmbaxed]

Please describe what you are requesting
There is no field for adding the name of user or system groups.

Describe what change you are proposing
Add a field like group_name for the group membership of user or system accounts.

Describe the log source
systemd
https://docs.nxlog.co/refman/current/im/systemd.html

Attach any sample logs or examples for details
There are many use cases where group names are provided as a context to the user which performed an action.