Set session priority

Assigns priority to a charging session (requires owner or service permissions).


Prioritized sessions are allocated before unprioritized ones and will receive
at least the prioritized current.

Important considerations:

• Multiple sessions can be prioritized; the caller must ensure enough available current.
  
• If there is insufficient current, prioritized sessions are allocated on a first-come, first-served basis.
  
• After allocating prioritized sessions, any remaining current is distributed among unprioritized sessions.