Group video by name

This is a feature we had on Android, we would need it in Medialibrary to prevent a regression.

Group videos by matching title start: group videos having the same first letter, the same 6 first letters or don't group.

We also ignored "The " substring for grouping.

Java implementation is here: https://code.videolan.org/videolan/vlc-android/blob/3.0.x/vlc-android/src/org/videolan/vlc/media/MediaGroup.java#L99