codec: Add libaribcaption for rendering ARIB STD-B24 caption

I'm new here. This MR adds a new caption renderer for the ARIB STD-B24 caption.

VLC already has ARIB caption support through libaribb24 as we all know. But it is a very preliminary implementation and does not have good text rendering effects. Meanwhile, the existing implementation lacks support for DRCS, which is a kind of bitmap font that is often used by Japanese TV stations.

Recently I have developed a new project libaribcaption for decoding and rendering ARIB STD-B24 based captions. It can render ARIB captions with the same effect as TV (or even better). Since libaribb24 seems to no longer be maintained, libaribcaption could be a good replacement for the current libaribb24-based implementation.

libaribcaption has some features that are currently unavailable in VLC:

• Rendering DRCS characters
• Support for Latin Languages (ABNT NBR 15606-1, used in South America countries)
• MIT License that makes it compatible with iOS App Store
• Good rendering effects that are even better than Japanese TV sets

For more information about libaribcaption, please move to https://github.com/xqq/libaribcaption

I hope this library could be utilized by VLC for improving ARIB caption support.

Best Regards,

xqq