return keep going when a state machine has changed its state

previously, when an animation advanced by 0 seconds, it would return true, which was interpreted as meaning that the animation needed to keep advancing.
We changed that behavior and now a linear animation will return false if it didn't advance.
A side effect of that is that now the animation state that calls advance, sets keepGoing to false instead of true.
So the animation wouldn't keep going in that frame.
Which is ok as long as we add a new condition to identify whether the state machine layer should keep going in the next frame based on whether it changed its state internally.
This PR adds that condition

Diffs=
51c3bbcde2 return keep going when a state machine has changed its state (#8564)

.rive_head

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-f34822a1249d46f46e6ca60daa6ea3f3045f3981
+51c3bbcde2dbd0c07d63ca2d1569f53aba668c23