Add type hints to SyncNode

[okapies]

• Add type hints to SyncNode
• Fix a type hint of Node.add_reference()
• Add the missing methods to SyncNode:
  • add_reference_type()
  • delete_reference()
  • get_access_level()
  • get_description_refs()
  • get_encoding_refs()
  • get_methods()
  • get_referenced_nodes()
  • read_data_type_definition()
  • read_event_notifier()
  • register()
  • set_attr_bit()
  • set_event_notifier()
  • unregister()
  • unset_attr_bit()
  • write_array_dimensions()
  • write_data_type_definition()
  • write_value_rank()

[oroulet]

you should also anotate the __init__method with reutrn value None so it gets checked by mypy. I have seen that you always skip that one into your MRs, but otherwise it looks good

[okapies]

Thanks. I'll put them later.