ReportQueue: remove HTTP post from locked section.
ReportQueue: remove HTTP post from locked section.

When the sender thread gets the lock, move any reports from the queue to
a local Json array. Then free the lock and try the send. If the send
succeeds, clear the array, otherwise keep it for the next attempt.

advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp