When DASH manifests have multiple audio AdaptationSets with the same representation IDs (e.g., both English and Japanese having id="0"), N_m3u8DL-RE would download the same track twice.
Now includes the language alongside the ID in selection args to properly disambiguate tracks across adaptation sets.
PR #38 refactored n_m3u8dl_re track selection to support DASH/ISM subtitle tracks, but this broke some subtitle downloads. Services that use direct URL downloads (Descriptor.URL) for subtitles, which n_m3u8dl_re does not support.
The track_selection function was using findall() to search for lang child elements, but in DASH manifests lang is an XML attribute on AdaptationSet. This caused language selection to fail for region-specific codes like es-419.
