Add check that setPlaybackSpeed is sane

This will ignore any values that are clearly incorrect i.e. <0.25.

This means the playback controller can still have a sentinel value of
-1.0 to ensure the model controlling speed is in-place correctly. Whilst
not breaking user playback by default if something goes wrong.

As this file directly interfaces with the video manager (which holds
surfaces) we can't easily make a test for it, so leave this block
untested

app/src/main/java/org/jellyfin/androidtv/ui/playback/VideoManager.java

@@ -417,6 +417,11 @@ public void setAudioTrack(int ndx, List<MediaStream> allStreams) {
     }
 
     public void setPlaybackSpeed(@NonNull Double speed) {
+        if (speed < 0.25) {
+            Timber.w("Invalid playback speed requested: %d", speed);
+            return;
+        }
+
         if (nativeMode) {
             mExoPlayer.setPlaybackSpeed(speed.floatValue());
         } else {