feat: core add particle stopped aborter (#1453)

simple aborter that checks if the particle is stopped and aborts propagation if so

Core/include/Acts/Propagator/StandardAborters.hpp

@@ -186,4 +186,25 @@ struct EndOfWorldReached {
   }
 };
 
+/// If the particle stopped (p=0) abort the propagation
+struct ParticleStopped {
+  ParticleStopped() = default;
+
+  /// boolean operator for abort condition without using the result
+  ///
+  /// @tparam propagator_state_t Type of the propagator state
+  /// @tparam stepper_t Type of the stepper
+  ///
+  /// @param [in,out] state The propagation state object
+  /// @param [in] stepper The stepper object
+  template <typename propagator_state_t, typename stepper_t>
+  bool operator()(propagator_state_t& state, const stepper_t& stepper) const {
+    if (stepper.momentum(state.stepping) > 0) {
+      return false;
+    }
+    state.navigation.targetReached = true;
+    return true;
+  }
+};
+
 }  // namespace Acts