extruder: expose `can_extrude` flag based on temperature

Sometimes an automated filament load is implemented,
but extruder might not always extrude filament.

This adds a flag to check if this operation is possible.

Signed-off-by: Kamil Trzcinski <ayufan@ayufan.eu>

docs/Status_Reference.md

@@ -144,6 +144,8 @@ The following information is available for heater objects such as
   the given heater.
 - `power`: The last setting of the PWM pin (a value between 0.0 and
   1.0) associated with the heater.
+- `can_extrude`: If extruder can extrude (defined by `min_extrude_temp`),
+  available only for [extruder](Config_Reference.md#extruder)
 
 # heaters
 

klippy/kinematics/extruder.py

@@ -91,6 +91,7 @@ class PrinterExtruder:
         self.pressure_advance_smooth_time = smooth_time
     def get_status(self, eventtime):
         return dict(self.heater.get_status(eventtime),
+                    can_extrude=self.heater.can_extrude,
                     pressure_advance=self.pressure_advance,
                     smooth_time=self.pressure_advance_smooth_time)
     def get_name(self):