Backward aligns the ts to the previous ts that divides by the interval, even if it is already aligned.

BackwardIfNotAligned aligns the ts to the previous ts that divides by the interval, except if it is already aligned.

Forward aligns ts to the next timestamp that divides by the interval, even if it is already aligned.

ForwardIfNotAligned aligns ts to the next timestamp that divides by the interval, except if it is already aligned.