Add decoder 7.1.4 output channel support

Since Android 12L, Android adds spatialization support. Decoder will output 7.1.4ch PCM to get better immersive experience, e.g. Dolby DD+JOC decoder.

library/common/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -1644,6 +1644,9 @@ public final class Util {
           // 8 ch output is not supported before Android L.
           return AudioFormat.CHANNEL_INVALID;
         }
+      case 12:
+        return Util.SDK_INT >= 32 ? AudioFormat.CHANNEL_OUT_7POINT1POINT4
+            : AudioFormat.CHANNEL_INVALID;
       default:
         return AudioFormat.CHANNEL_INVALID;
     }