OARIS3 — Heartbeat required as the basis for on_requested_deadline_missed for DDS PSM

The Exchange Heartbeat use case supports assurance cases relating to runtime software integrity, in particular that critical functionality continues to be available and has not failed silently.
For the DDS PSM this is currently mapped to the built-in DDS API, but the on_requested_deadline_missed requires a suitable topic definition (which could/should be provided by the Exchange Heartbeat use case).

Defer to 3.1 RTF

This issue was raised against OARIS 2.0 and transferred into the OARIS 3.0 FTF very recently and after the comment deadline. In order to not delay the OARIS 3.0 FTF it is proposed to defer this issue for resolution in OARIS 3.1 which will be chartered at the successful conclusion of this FTF.