Add unary minus operator to vector

Signed-off-by: Andreas Rauschert <andreas.rb.rauschert@bmw.de>

MantleAPI/include/MantleAPI/Common/vector.h

@@ -29,6 +29,11 @@ struct Vec3
   T z{0};
 
   inline T Length() const { return units::math::sqrt((x * x) + (y * y) + (z * z)); }
+
+  inline Vec3<T> operator-() const noexcept
+  {
+    return {-x, -y, -z};
+  }
 };
 
 template <typename T>