bed_screws: Add a helper tool for leveling bed screws

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

test/klippy/bed_screws.cfg

@@ -0,0 +1,50 @@
+# Test config for bed screws tool
+[stepper_x]
+step_pin: ar54
+dir_pin: ar55
+enable_pin: !ar38
+step_distance: .0125
+endstop_pin: ^ar3
+position_endstop: 0
+position_max: 200
+homing_speed: 50
+
+[stepper_y]
+step_pin: ar60
+dir_pin: !ar61
+enable_pin: !ar56
+step_distance: .0125
+endstop_pin: ^ar14
+position_endstop: 0
+position_max: 200
+homing_speed: 50
+
+[stepper_z]
+step_pin: ar46
+dir_pin: ar48
+enable_pin: !ar62
+step_distance: .0025
+endstop_pin: ^ar18
+position_endstop: 0.5
+position_max: 200
+
+[bed_screws]
+screw1: 100,50
+screw1_name: Front right
+screw1_fine_adjust: 200,50
+screw2: 75,75
+screw2_fine_adjust: 200,75
+screw3: 75,75
+screw3_name: Last
+screw3_fine_adjust: 75,90
+
+[mcu]
+serial: /dev/ttyACM0
+pin_map: arduino
+
+[printer]
+kinematics: cartesian
+max_velocity: 300
+max_accel: 3000
+max_z_velocity: 5
+max_z_accel: 100