common/playlist: don't allocate duplicated playlist_path

[kasper93]

If the playlist is loaded directly from a protocol like memory://, the playlist_path represents the entire playlist. In cases where we have a large playlist, this results in the entire playlist being duplicated for each item. For example, if the input size is 300 kB with 10k items, we end up using 3 GB of memory just to store the playlist_path strings.

[github-actions[bot]]

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[zsugabubus]

Sorry if I'm stating the obvious, I just would like to note that long memory:// will still remain very inefficient (=unusable) because playlist property keeps serializing that huge playlist_path for each entry.

[kasper93]

Indeed, it is quite problematic, might fix that in the future. For now at least it will not OOM like crazy...

[llyyr]

Open a ticket so it's not memory-holed