This came up in a recent #animation_rigging meeting.
Previously only keyframes themselves were supported in Graph Editor
snapping, now suport this for handles as well.
As an example, only the `Selection to Current Frame` is supported here
to gather feedback.
- `only keyframe is selected`: just the keyframe moves in time (both handles stay exactly [absolute] where they are)
- `only handle is selected`: just the handle gets snapped, the keyframe stays exactly [absolute] where it is
- `one handle plus keyframe selected`: the keyframe gets snapped, the selected handle keeps it relative offset, the unselected handle stays exactly where it is
- `both handles plus keyframe selected` : keyframe gets snapped, both handles keep their relative distance (just is most like the transform system
(atm - current master - only the keyframe snaps, the handles always stay exactly where they are)
{F12805325}
ref T94174