Implement utility functions to check if we have content or notif session with device

Summary: This differential implements simple utility functions to check if we have session for both content and/or notifs with particular device.

Test Plan: Tested in D12673

Reviewers: bartek, tomek, kamil

Reviewed By: tomek, kamil

Subscribers: kamil, ashoat

Differential Revision: https://phab.comm.dev/D12672