[DVDInputStreamNavigator/Players] Use a struct and dvdnav_get_audio_info(...) to query all required audio stream info at once.

[Fixes]
- Fix stream type, e.g. "(Directors Comments)", recognition. It is stored in code_extension not in lang_extension.

- Properly set the number of channels of a dvd audio stream.

- Set the stream language of dvd audio tracks properly/consistent with other audio streams, i.e. set it to a three char code.

- Set the stream name of dvd audio tracks properly/consistent with other audio streams.
[DVDInputStreamNavigator/Players] Use a struct and dvdnav_get_stitle_info(...) to query all required subtitle stream info at once.

[Fixes]
- Set the stream language of dvd subtitles properly/consistent with other streams, i.e. set it to a three char code.

- Set the stream name of dvd subtitle tracks properly/consistent with other streams; in particular don't use the language as the name.
Make the type, e.g. "(Forced)", of a stream translatable in its name.
[DVDDemuxer] Don't set the language as the stream name.
[Players] Don't assign "unknown" to the audio/subtitle stream name, leave it empty instead.
[AMLPlayer] Set the name of a stream properly/consistent with the other players, i.e., codec name (if possible) + channels.
Don't assign "unknown" to the audio/subtitle stream name, leave it empty instead.
[Players] Convert the language code of a selection stream to three chars if necessary.
[AMLPlayer] Convert the language code of a stream to three chars if necessary.
[AMLPlayer] Always set the name and language fields of a subtitle/audio stream in the getInfo methods.
[Players] Set the  language code instead of the full name in the GetSubtitleStreamInfo methods.
[GUI Audio] Adapt the presentation of audio and subtitle items. The labels are built as follows:
"[language|unknown] - name" or, if name is empty, "[language/unknown]"
[DVDDemux] Add "Dolby TrueHD" and 7.1 recognition to GetStreamType. Additionally adapt the default channel string to "channel count-chs"
[Player] Return the language code of a stream, or its name if the language is not specified.
[Fix] Correct the audio format recognition.
[Cosmetics] Fix indentations.
[Fix] Fixes dvdnav_audio_stream_format(...). Don't change the audio format numbers, e.g. DTS is 6 not 5, 5 is unknown.
Merge pull request #2162 from ace20022/unify_stream_lang

Unify the assignment and usage of the name and language of streams