Move RepeatModeUtil to common

It's used by the UI and mediasession modules. We may be able to move
it into the UI module if/when the mediasession module goes away.

PiperOrigin-RevId: 356734939

library/core/src/main/java/com/google/android/exoplayer2/util/RepeatModeUtil.java → library/common/src/main/java/com/google/android/exoplayer2/util/RepeatModeUtil.java

@@ -91,5 +91,4 @@ public final class RepeatModeUtil {
         return false;
     }
   }
-
 }