Effect: Clarify FrameProcessingException javadocs.

This is confusing, since the effect is used not only when applying an effect, but also when preparing an effect (ex. in a texture processor's constructor), so we should also mention that case.

PiperOrigin-RevId: 504843598

libraries/common/src/main/java/androidx/media3/common/FrameProcessingException.java

@@ -17,7 +17,10 @@ package androidx.media3.common;
 
 import androidx.media3.common.util.UnstableApi;
 
-/** Thrown when an exception occurs while applying effects to video frames. */
+/**
+ * Thrown when an exception occurs while preparing an {@link Effect}, or applying an {@link Effect}
+ * to video frames.
+ */
 @UnstableApi
 public final class FrameProcessingException extends Exception {