[PACKAGEGROUP] Add system utilities packagegroup

The packagegroup-seco-system is always included in the image.

The packagegroups:

• packagegroup-seco-system-file-editor
• packagegroup-seco-system-serial-tools
• packagegroup-seco-system-monitoring-tools
• packagegroup-seco-system-disk-utilities
• packagegroup-seco-system-package-manager

are added depending on the variables set by the configurator.

JIRA Reference: [CLEAOS-772]

Signed-off-by: Nicola Sparnacci nicola.sparnacci@seco.com