Improve a few APIs in `Pipeline` to reducing the amount of copying. A few APIs have been changed to accept a larger parameter by const reference instead of by value, which avoids copying the parameter value.

Also, for Pipeline APIs that internally rewrite the pipeline steps into vectors, reserve enough capacity in these vectors so they can store the full results without having to re-allocate and copy/move the values when resizing the vectors after individual inserts.

As an unrelated change, also removes `using boost::intrusive_ptr` in `Pipeline.cpp` and replace all unqualified occurrences with the FQN.