Maybe an error in propogate.cpp when construct discrete noise covariance matrix

[WZG3661]

In Propagate.cpp: https://github.com/rpng/open_vins/blob/17b73cfe4b870ade0a65f9eb217d8aab58deae19/ov_msckf/src/state/Propagator.cpp#L459-L466 why the covariance of bias is divided by dt not multiplied but in the doc of IMU Propagation: the covariance of bias is multiplied by dt and in fast_state_propagate: https://github.com/rpng/open_vins/blob/17b73cfe4b870ade0a65f9eb217d8aab58deae19/ov_msckf/src/state/Propagator.cpp#L220-L228

[a4saran]

The missing dt is added in G in the function _compute_F_and_Ganalytic and _compute_F_and_Gdiscrete

https://github.com/rpng/open_vins/blob/17b73cfe4b870ade0a65f9eb217d8aab58deae19/ov_msckf/src/state/Propagator.cpp#L960-L961

[WZG3661]

Thanks a lot!