Replace removed `WrmHeader.read_attributes()` with `key_ids` property and add missing WRMHEADER v4.1-v4.3 XML paths (`DATA/PROTECTINFO/...`) to the base64 PSSH parser fallback.
Session keys from master playlists often contain PSSHs with multiple KIDs covering all tracks, causing licensing to return keys for wrong KIDs.
Changes:
- Unified DRM licensing logic for all downloaders
- Prefer media playlist EXT-X-KEY tags which contain track-specific KIDs
- Add filter_keys_for_cdm() to select keys matching configured CDM type
- Add get_track_kid_from_init() to extract KID from init segment with fallback to drm.kid from PSSH
- Track initial_drm_key to prevent double-licensing on first segment
- Simplify n_m3u8dl_re block to reuse common licensing flow
- Use strict PlayReady keyformat matching via PR_PSSH.SYSTEM_ID URN instead of loose substring match
- Fix PlayReady keyformat comparisons that incorrectly compared strings to PlayReadyCdm class
- Fix byterange header format in get_track_kid_from_init() to use HLS.calculate_byte_range()
Also fixes PlayReady keyformat matching in:
- unshackle/core/tracks/track.py
- unshackle/core/drm/playready.py
Fixes download failures where track_kid was null or mismatched, causing wrong content keys to be obtained during PlayReady/Widevine licensing.
Remove erroneous `.bytes` accessor from PSSH.SYSTEM_ID comparisons in from_track() and from_init_data() methods. The pyplayready PSSH.SYSTEM_ID is already the correct type for comparison with parsed PSSH box system_ID values.
* Introduced a new configuration option for DRM decryption in `unshackle.yaml`.
* Updated the `decrypt` methods in `PlayReady` and `Widevine` classes to allow using `mp4decrypt`.
* Enhanced the `Config` class to manage decryption methods per service.
* Added `mp4decrypt` binary detection in the binaries module.
