TaskQueueProducer constructor requires a ReactESP pointer

There was a major bug in the previous TaskQueueProducer implementation:
values were always received in the main task context. This commit adds
a new constructor argument in which a subtask app pointer can be
provided, allowing queued items to be consumed in a subtask.

A constructor variant without the argument is also provided for
backwards compatibility.

src/sensesp/net/ws_client.h

@@ -90,7 +90,7 @@ class WSClient : public Configurable,
   bool token_test_success_ = false;
 
   TaskQueueProducer<WSConnectionState> connection_state_ =
-      TaskQueueProducer<WSConnectionState>(WSConnectionState::kWSDisconnected);
+      TaskQueueProducer<WSConnectionState>(WSConnectionState::kWSDisconnected, ReactESP::app);
 
   /// task_connection_state is used to track the internal task state which might
   /// be out of sync with the published connection state.
@@ -100,7 +100,7 @@ class WSClient : public Configurable,
   WebSocketsClient client_;
   SKDeltaQueue* sk_delta_queue_;
   TaskQueueProducer<int> delta_count_producer_ =
-      TaskQueueProducer<int>(0, 5, 990);
+      TaskQueueProducer<int>(0, ReactESP::app, 5, 990);
 
   SemaphoreHandle_t received_updates_semaphore_ =
       xSemaphoreCreateRecursiveMutex();

src/sensesp/system/task_queue_producer.h

@@ -1,6 +1,7 @@
 #ifndef SENSESP_SYSTEM_TASK_QUEUE_PRODUCER_H_
 #define SENSESP_SYSTEM_TASK_QUEUE_PRODUCER_H_
 
+#include "ReactESP.h"
 #include "observablevalue.h"
 
 namespace sensesp {
@@ -14,13 +15,14 @@ namespace sensesp {
  * in another.
  *
  * @tparam T
+ * @param consumer_app The app object in which the values should be consumed.
  * @param queue_size Size of the queue.
  * @param poll_rate How often to poll the queue. Note: in microseconds!
  */
 template <class T>
 class TaskQueueProducer : public ObservableValue<T> {
  public:
-  TaskQueueProducer(const T& value, int queue_size = 1,
+  TaskQueueProducer(const T& value, reactesp::ReactESP* consumer_app = ReactESP::app, int queue_size = 1,
                     unsigned int poll_rate = 990)
       : ObservableValue<T>(value), queue_size_{queue_size} {
     queue_ = xQueueCreate(queue_size, sizeof(T));
@@ -29,14 +31,17 @@ class TaskQueueProducer : public ObservableValue<T> {
     }
 
     // Create a repeat reaction that will poll the queue and emit the values
-    ReactESP::app->onRepeatMicros(poll_rate, [this]() {
+    consumer_app->onRepeatMicros(poll_rate, [this]() {
       T value;
       while (xQueueReceive(queue_, &value, 0) == pdTRUE) {
         this->emit(value);
       }
     });
   }
 
+  TaskQueueProducer(const T& value, int queue_size = 1, unsigned int poll_rate = 990)
+      : TaskQueueProducer(value, ReactESP::app, queue_size, poll_rate) {}
+
   bool set(const T& value) {
     int retval;
     if (queue_size_ == 1) {