Design object 'observed at' moment in time option in report flow

[RomijnHumanoids]

As a user, I want to be able to generate a report based on a (timestamped) situation in the past.
Design needs to include:

• When selecting objects, all objects in a report are from one moment in time.
• The possibility to select this and its effects on the report generation need to be clear to the user.

[RomijnHumanoids]

After discussing the matter with openKAT design team we conclude to make the timestamp selection as first step in the generate report flow. The subsets in the next pages are depending on the selected timestamp in the first step: objects, report types (openKAT version at the time) etc.

[noamblitz]

@dekkers will first put all different "times" in this tickets and we discuss the "normal human translations" next week.