Improve setting of the `updated_at` and `updated_by` entries

With @tim.eder & @kotyba.alhaj-taha we discussed that we want to list latest updated entites in the frontend, in order to show the user latest activities (in sms overall, in their groups, or only their own ones is not completely sure yet).

However, in order to extract latest updates we suggest to have some changes:

• The creation also sets the updated_at and updated_by (so that we can sort for this one only)
• Adding/editing/removing related objects should update updated_at & updated_by entries for the main entities. Affected are:
  • devcies:
    • device contact roles
    • device properties
    • customfields
    • attachments
    • device specific actions (I would suggest that we keep the mount actions seperate, they don't change any real data associated with the device)
  • platforms:
    • platform contact roles
    • attachments
    • platform specific actions (similar to devices: lets keep the mount actions seperate)
  • configurations
    • configuration contact roles
    • mount actions
    • location actions
    • generic configuration actions

This way we can show where are the latest changes on one of the entities & display those to the user.