Keep printer-agent progress in sync

Keep the shared task progress aligned with agent
reports that lack Bambu cloud task identity.

Release the lazily allocated task during reset to
avoid leaks when machine objects reconnect.

tests/slic3rutils/CMakeLists.txt

@@ -2,6 +2,7 @@ get_filename_component(_TEST_NAME ${CMAKE_CURRENT_LIST_DIR} NAME)
 add_executable(${_TEST_NAME}_tests
     ${_TEST_NAME}_tests_main.cpp
     test_dev_mapping.cpp
+    test_device_progress.cpp
     test_network_versions.cpp
     test_action_source.cpp
     test_plugin_host_api.cpp