Per-app firewall rule: Block while roaming

[ignoramous]

A user says,

What I like in Netguard is the possibility to block apps from accessing the internet while roaming. Unfortunately this feature is missing here, cause I can only block mobile networks in general.

roaming is a network capability. Traceable in ConnectionMonitor.kt but needs additional UI (to add a new icon/rule in apps screen) and DB changes (to store the rule).