refactor: improve `ConnectivityManager` extensions

app/src/main/java/com/geeksville/mesh/repository/network/ConnectivityManager.kt

@@ -6,18 +6,24 @@ import android.net.NetworkRequest
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.map
 
-internal fun ConnectivityManager.networkAvailable(): Flow<Boolean> = callbackFlow {
+internal fun ConnectivityManager.networkAvailable(): Flow<Boolean> =
+    allNetworks().map { it.isNotEmpty() }.distinctUntilChanged()
+
+internal fun ConnectivityManager.allNetworks(
+    networkRequest: NetworkRequest = NetworkRequest.Builder().build(),
+): Flow<Array<Network>> = callbackFlow {
     val callback = object : ConnectivityManager.NetworkCallback() {
         override fun onAvailable(network: Network) {
-            trySend(allNetworks.isNotEmpty())
+            trySend(allNetworks)
         }
 
         override fun onLost(network: Network) {
-            trySend(allNetworks.isNotEmpty())
+            trySend(allNetworks)
         }
     }
-    val networkRequest = NetworkRequest.Builder().build()
     registerNetworkCallback(networkRequest, callback)
 
     awaitClose { unregisterNetworkCallback(callback) }