Changes planned for post v5.2.0

[PawelPlesniak]

Here are all the changes we're planning for after the release of v5.2.0, including

• Missing commit from a previous PR, details here
• Used a ProcessQuery for terminate, not required. Details here
• Daemon process_manager. Details here

Requires

• https://github.com/DUNE-DAQ/daqsystemtest/pull/155