Fix default subtitle track selection

[1hitsong]

Changes

Add code to determine which subtitle to select and enable by default - without the user needing to manually select it.

Several functions were copied from subtitles.bs. Once we're fully on the new global queue player, this file should no longer be needed.

Modify selection logic to be:

Default: IsForced, IsDefault

Always: IsForced, IsDefault, isExternal

OnForced: IsForced

Smart: 
if audio languge <> preferred subtitle language
	Search for match where subtitle.language = preferred subtitle language
		IsForced, IsDefault, IsExternal
	if no match found, fallback to default methodology
		IsForced, IsDefault

Issues

Fixes #1571
Fixes #850

[cewert]

This fixes #1571. Is there anything else that needs tested with the copied functions?

[1hitsong]

The big things are ensuring the selection paths work as expected, and that the language check works.

I had to update the language selection code because it was not selecting any subtitle by default because my SubtitleLanguagePreference is set to "Any Language" on the server, which equals "" in code. This caused the language check to never pass.

[lakerssuperman]

I just tried this and it didn't work unfortunately. Watching a movie with a forced subtitled track results in the following:

1. The forced track is shown to be selected in the subtitle selection dialog.
2. The forced subtitles are not displayed during playback.

If I manually toggle subtitles off and then back on it will display the subtitles. However, if I then go to another movie with standard English not forced subtitles those will be displayed as well despite the subtitle selection dialog indicating subtitles are off. Clicking None, even if it is already selected and then clicking ok turns subtitles back off.

[1hitsong]

Can you post a screenshot of your subtitle settings on the server? Specifically the 1st 3 items, Preferred subtitle language, Subtitle mode, and Burn subtitles.

[lakerssuperman]

Can you post a screenshot of your subtitle settings on the server? Specifically the 1st 3 items, Preferred subtitle language, Subtitle mode, and Burn subtitles.

Let me know if you need anything else! Thanks!