Temporary Wi-Fi hotspot for bypassing tethering limits (#18)

* First draft of temporary hotspot
* Refactor with LocalOnlyInterfaceManager
* Refactor LocalOnlyHotspotService
* Localize
* Update strict summary

mobile/src/main/java/be/mygod/vpnhotspot/IpNeighbourMonitoringService.kt

@@ -0,0 +1,24 @@
+package be.mygod.vpnhotspot
+
+import android.app.Service
+import be.mygod.vpnhotspot.net.IpNeighbour
+import be.mygod.vpnhotspot.net.IpNeighbourMonitor
+
+abstract class IpNeighbourMonitoringService : Service(), IpNeighbourMonitor.Callback {
+    private var neighbours = emptyList<IpNeighbour>()
+
+    protected abstract val activeIfaces: List<String>
+
+    override fun onIpNeighbourAvailable(neighbours: Map<String, IpNeighbour>) {
+        this.neighbours = neighbours.values.toList()
+    }
+    override fun postIpNeighbourAvailable() {
+        val sizeLookup = neighbours.groupBy { it.dev }.mapValues { (_, neighbours) ->
+            neighbours
+                    .filter { it.state != IpNeighbour.State.FAILED }
+                    .distinctBy { it.lladdr }
+                    .size
+        }
+        ServiceNotification.startForeground(this, activeIfaces.associate { Pair(it, sizeLookup[it] ?: 0) })
+    }
+}