Mugwanya KK, Matemo D, Scoville CW, Beima-Sofie KM, Meisner A, Onyango D, Mugambi M, Feutz E, Grabow C, Barnabas R, Weiner B, Baeten JM, Kinuthia J; FP Plus Team. Integrating PrEP delivery in public health family planning clinics: a protocol for a pragmat