klippy: Convert printer_state("connect") to an event handler

Convert all users of the printer_state("connect") handler to register
a "klippy:connect" event handler instead.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/z_tilt.py

@@ -9,6 +9,8 @@ import probe, mathutil
 class ZTilt:
     def __init__(self, config):
         self.printer = config.get_printer()
+        self.printer.register_event_handler("klippy:connect",
+                                            self.handle_connect)
         z_positions = config.get('z_positions').split('\n')
         try:
             z_positions = [line.split(',', 1)
@@ -27,9 +29,6 @@ class ZTilt:
         self.gcode.register_command(
             'Z_TILT_ADJUST', self.cmd_Z_TILT_ADJUST,
             desc=self.cmd_Z_TILT_ADJUST_help)
-    def printer_state(self, state):
-        if state == 'connect':
-            self.handle_connect()
     def handle_connect(self):
         kin = self.printer.lookup_object('toolhead').get_kinematics()
         z_steppers = kin.get_steppers('Z')