Add probe_switch_activated

Marlin/src/module/endstops.h

@@ -116,6 +116,14 @@ class Endstops {
       ;
     }
 
+    static inline bool probe_switch_activated() {
+      return (true
+        #if ENABLED(PROBE_ACTIVATION_SWITCH)
+          && READ(PROBE_ACTIVATION_SWITCH_PIN) == PROBE_ACTIVATION_SWITCH_STATE
+        #endif
+      );
+    }
+
     /**
      * Report endstop hits to serial. Called from loop().
      */