Enabled deletion of files created by the range-test module

src/modules/RangeTestModule.h

@@ -44,6 +44,11 @@ class RangeTestModuleRadio : public SinglePortModule
      */
     bool appendFile(const meshtastic_MeshPacket &mp);
 
+    /**
+     * Cleanup range test data from filesystem
+     */
+    bool removeFile();
+
   protected:
     /** Called to handle a particular incoming message