Fix gcode_move initialize in toolchanger.py

[fiferboy]

I was getting the following error when using the toolchanger.py module:

Config error
Traceback (most recent call last):
  File "/home/pi/klipper/klippy/klippy.py", line 175, in _connect
    self._read_config()
  File "/home/pi/klipper/klippy/klippy.py", line 141, in _read_config
    self.load_object(config, section_config.get_name(), None)
  File "/home/pi/klipper/klippy/klippy.py", line 130, in load_object
    self.objects[section] = init_func(config.getsection(section))
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/klipper/klippy/extras/tool.py", line 140, in load_config_prefix
    return Tool(config)
           ^^^^^^^^^^^^
  File "/home/pi/klipper/klippy/extras/tool.py", line 18, in __init__
    self.main_toolchanger = self.printer.load_object(config, 'toolchanger')
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/klipper/klippy/klippy.py", line 130, in load_object
    self.objects[section] = init_func(config.getsection(section))
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/klipper/klippy/extras/toolchanger.py", line 383, in load_config
    return result
           ^^^^^^^
  File "/home/pi/klipper/klippy/extras/toolchanger.py", line 26, in __init__
    #        self.gcode_move = self.printer.lookup_object('gcode_move')
                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/pi/klipper/klippy/klippy.py", line 97, in lookup_object
    raise self.config_error("Unknown config object '%s'" % (name,))
configparser.Error: Unknown config object 'gcode_move'

This change initializes self.gcode_move in a consistent manner with other modules that use it (probe.py, gcode_arcs.py, and some other modules from this repo like tool_probe.py and tools_calibrate.py) and removes the error for me.

[viesturz]

Thanks for the fix. Merged.