negative speed fix

negative speed states wouldn't play the animation if it didn't have transition duration or exit time.
this PR fixes it by taking into account the speed multiplier when evaluating if the animation still has frames to play.

Diffs=
0bc446fad negative speed fix (#6982)

Co-authored-by: hernan <hernan@rive.app>

.rive_head

@@ -1 +1 @@
-f832e26172cfbd11d52114ebb667e13418a5b1cd
+0bc446fad2a568a7088fdaa122af0de2de1dc940

include/rive/animation/linear_animation_instance.hpp

@@ -69,6 +69,13 @@ class LinearAnimationInstance : public Scene
                (directedSpeed() < 0 && m_time > m_animation->startSeconds());
     }
 
+    bool keepGoing(float speedMultiplier) const
+    {
+        return this->loopValue() != static_cast<int>(rive::Loop::oneShot) ||
+               (directedSpeed() * speedMultiplier > 0 && m_time < m_animation->endSeconds()) ||
+               (directedSpeed() * speedMultiplier < 0 && m_time > m_animation->startSeconds());
+    }
+
     float totalTime() const { return m_totalTime; }
     float lastTotalTime() const { return m_lastTotalTime; }
     float spilledTime() const { return m_spilledTime; }

src/animation/linear_animation_instance.cpp

@@ -58,7 +58,7 @@ bool LinearAnimationInstance::advance(float elapsedSeconds, KeyedCallbackReporte
     // NOTE:
     // do not track spilled time, if our one shot loop is already completed.
     // stop gap before we move spilled tracking into state machine logic.
-    bool killSpilledTime = !this->keepGoing();
+    bool killSpilledTime = !this->keepGoing(elapsedSeconds);
 
     float lastTime = m_time;
     m_time += deltaSeconds;
@@ -165,7 +165,7 @@ bool LinearAnimationInstance::advance(float elapsedSeconds, KeyedCallbackReporte
     }
 
     m_didLoop = didLoop;
-    return this->keepGoing();
+    return this->keepGoing(elapsedSeconds);
 }
 
 void LinearAnimationInstance::time(float value)