Artist info page: Combine commentary entries with same annotation

[towerofnix]

That is, provided two commentary entries for the same thing (a track, an album itself, or a flash), then if they have the same annotation text (before processing), or if neither has annotation text at all, those entries should be combined.

The intent is not to combine two entries for the same thing together under all circumstances—only to avoid cases where an item that looks exactly the same is duplicated, providing no additional information.

If a thing has two commentary entries and only one of them has an annotation, for the moment we're planning not to combine them—but we could show a placeholder and dimmed-out annotation instead, like "no annotation". Things with only a single commentary entry (after dedup) which has no annotation should not show this "no annotation" text—it's just for disambiguating when another entry for the same thing does have an annotation.

Thanks Makin, via #issuefication-zone.

[towerofnix]

An easier, no-magic way to handle this would be to just combine the entries under a <details> toggle, with the custom annotation "multiple entries"... but it is nice to see all the (distinct) entries up front, so maybe we don't want to put them behind a toggle.