Retain the video engine in the call service before starting its workers

tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallService.kt

@@ -275,6 +275,7 @@ class CallService : Service() {
             check(audio.start(id)) { "audio engine rejected start" }
             operation = "video"
             video = CallVideoEngine(this, id)
+            video!!.start()
             LogManager.addLog("INFO", "CallService", "audio/video started id=$id")
             return true
         } catch (e: Exception) {

tools/chatgui-android/call-service-tests/src/main/kotlin/com/utun/chat/data/CallServiceHost.kt

@@ -51,6 +51,7 @@ class CallVideoEngine(context: Context, val id: Long) {
     var stopped = false; var stops = 0
     val state = MutableStateFlow(CallVideoState())
     val display = MutableStateFlow<Any?>(null)
+    fun start() { check("start" !in failures) { "video startup unavailable" } }
     fun select(settings: CallVideoSettings) { state.value = CallVideoState(settings) }
     fun stop(): Boolean {
         stops++