Add atmospheric drag effect for Brouwer-Lyddane model
This issue is related to the discussion during the fix of #869 (closed). Warren Phipps's 1992 thesis  presents an analytical model for the atmospheric drag that is suited for the Brouwer-Lyddane orbit propagator.
Reference  highlights the benefits of the drag augmented Brouwer-Lyddane orbit propagator for low Earth satellite orbit determination. Therefore, having this new feature could be interesing.