core: add User,Group,SupplementaryGroups,Nice to varlink
Unit.StartTransient
This commit adds more writable fields to the
io.systemd.Unit.StartTransient
varlink method. With this its possible to set:
User,Group,SupplementaryGroups,Nice values.
Plus tests for them.
---
core: report unsupported service fields in varlink calls
Just like for the unsupported/bad exec_fields we should show
a message about what field is bad for service parameters. This
commit adds it using the same pattern. The JSON parser works in
fail-fast mode so we only display the first bad field (and
it depends on the parser what it finds first).
Daan De Meyer
a080cb356c