flint: goto_click only move 1 motor

Feedback from @berruyer and ID14.

Move on click, move the motor at the clicked location.

For a2scan, a single motor is moved.

One would like to move every motors at position the motors was at the time of the position the user click.

It's a change of behavior.

It's maybe better to use another function for that use case, or enable that behaviour with a flag.

goto_click(all=True)

or

goto_click_all()

or

goto_click_time()
# because a mapping will have to be done from pos -> elapsetime -> every pos