Add use_self_delta_to_fade to NodeOneShot to fade finished animation

[TokageItLab]

• Fixes OneShots can't fade out StateMachine shots with no running animation #101169

First, note that this is a band-aid solution.

For example, when there is a 1 second fade in OneShot, when the input TimeScale is 2.0, the fade is actually 0.5 seconds.

This is a fix to address the problem noted in #87009 and to keep the past behavior that has existed since 3.x, but I assume it is not correct in terms of consistency.

For complete consistency, I think the NodeTimeInfo should include the TimeScale and get the remaining time depending on that. However, this is a major rework and should not be done at this stage as it would be a significant behavior change. So, I believe we should rethink this when the update timing to 5.0. (So this and #101792 using prediction.)

For now, enabling this option will allow the fade to work even when the input animation delta is 0.

[TokageItLab]

I sent #101792 as an alternative. I think that is a smarter solution as it does not add any extra options.

[TokageItLab]

Superseded by #101792.