Allow retrieving ground station transforms at date already considering clock offset
The GroundStation.getOffsetToInertial
methods always consider the specified date is the measurement date read at ground station, and the method add the clock offset to build a transform at the corresponding physical date.
In some cases (for example in modifiers), the clock offset has already been considered as it was compensated when building the participants array.
So the GroundStation.getOffsetToInertial
methods should also allow providing a date that already included the clock compensation.
Edited by Luc Maisonobe