Add clear queue api (#171)

* Add clear queue api

* Minor improvement

* Update changelog

---------

Co-authored-by: Foti Dim <foti@navideck.com>

lib/src/universal_ble.dart

@@ -414,6 +414,12 @@ class UniversalBle {
     );
   }
 
+  /// Clear a queue.
+  /// Use [BleCommandQueue.globalQueueId] to clear the global queue.
+  /// To clear the queue of a specific device, use `deviceId` as [id].
+  /// If no [id] is provided, all queues will be cleared.
+  static void clearQueue([String? id]) => _bleCommandQueue.clearQueue(id);
+
   /// [receivesAdvertisements] returns true on web if the browser supports receiving advertisements from a certain `deviceId`.
   /// The rest of the platforms will always return true.
   /// If true, then you will be getting scanResult updates for this device.

lib/src/utils/ble_command_queue.dart

@@ -51,4 +51,14 @@ class BleCommandQueue {
     _queueMap[id] = queue;
     return queue;
   }
+
+  void clearQueue(String? id) {
+    if (id == null) {
+      _queueMap.forEach((k, v) => v.dispose());
+      _queueMap.clear();
+    } else {
+      _queueMap[id]?.dispose();
+      _queueMap.remove(id);
+    }
+  }
 }