added parameter which defines threshold for airspeed given to the filter

msg/ekf2_replay.msg

src/modules/ekf2/ekf2_main.cpp

src/modules/ekf2/ekf2_params.c

src/modules/ekf2_replay/ekf2_replay_main.cpp

src/modules/sdlog2/sdlog2.c

src/modules/sdlog2/sdlog2_messages.h