playlist/item: utilize TAB_FIND in ItemIndex
playlist/item: utilize TAB_FIND in ItemIndex

Even though this results in more lines than the previous
implementation, it should be easier to read and reason about the
implementation using the already defined helper for finding entities
within a vlc TAB.

Signed-off-by: Thomas Guillem <5f50a84c1fa3bcff146405017f36aec1a10a9e38@gllm.fr>

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc