input: fix playlist track data overriding issue in CUE file

Fixes #4143 (closed)

In a vlc_meta_t object, each metadata key is associated with a priority: VLC_META_PRIORITY_BASIC, VLC_META_PRIORITY_PLAYLIST, or VLC_META_PRIORITY_INBAND. During metadata merging, keys with higher or equal priority can override those with lower priority. When parsing playlist metadata from a CUE file, keys are now assigned a priority of VLC_META_PRIORITY_PLAYLIST. This change prevents subsequent audio files, which have VLC_META_PRIORITY_BASIC, from overriding the playlist metadata. Additionally, this commit ensures that the duration of individual tracks is calculated using the 'start-time' and 'stop-time' options. This prevents the total track duration from overriding the individual track durations in the playlist.

Sample CUE file: soft-rock-CD.cue

Screenshot: