feat(meta,core,app,android,ios): AniSkip where files have no chapters

Most files that are not fansub releases carry no chapters, so they had no
skip button. AniSkip knows where an episode's opening and ending are, by
MyAnimeList id and episode number. ani.zip sends each entry's MyAnimeList
id and enrichment now keeps it on every episode row; schema v14 adds the
column and marks AniList titles un-enriched, deleting nothing, as v13 did.

When a file has loaded with no chapter naming an opening or ending, and
its length is known, each client asks once, with enrichment on only. The
answer lives as long as the file is open. with_skip_ranges cuts it into
the chapters as chapters named Opening and Ending, so the skip button,
auto-skip, the up-next countdown and the seek bar's marks all work
through the code a chaptered file uses. A file's own opening or ending
always wins over AniSkip's.

PRIVACY.md lists what is sent: the MyAnimeList id, the episode number and
the file's length.

docs/PRIVACY.md

@@ -11,6 +11,7 @@ and to nothing else unless you turn on posters and descriptions. This page lists
 | AniList and ani.zip, or TMDB | The names of the titles in your library, and the ids of matched titles | Only with **Posters and descriptions** on |
 | TVmaze | With AniList chosen: the names of the titles AniList has no match for, and the ids of those TVmaze matched | Only with **Posters and descriptions** on |
 | TMDB, with AniList chosen | The TMDB ids of matched titles that have no wide picture or logo yet. Never a title's name | Only with **Posters and descriptions** on and a TMDB key saved |
+| AniSkip | The MyAnimeList id and episode number of what you play, and the file's length. Never a name | Only with **Posters and descriptions** on, when you play an episode whose file does not mark its opening and ending |
 
 Nothing else leaves your device. There is no telemetry, no crash reporting and no update check.