Group-ordinal within the same-identity set (a preceding different-language
track no longer makes the first duplicate unreachable), exclude server-burned
(Encode) streams from the embedded ordinal and signal them as burnedIn, match
languages across ISO 639-1/639-2 B-T/IETF variants, and sort the menu by the
raw IsExternal flag so the order stays stable between direct play and transcode.
Adds getExternalSubtitleUrl as the single source of truth for the external-sub
URL, and short-circuits disable/burnedIn before enumerating the track list.
14ea18e0d2