Add support for thumbfast (thumbnails on seekbar)

[ShoaibKhanali]

Hi, thanks for your great work on mpvkt!

Can you please add support for https://github.com/po5/thumbfast/?tab=readme-ov-fileAdd support for Thumbfast is a tool that generates timeline thumbnails, similar to the previews seen on platforms like YouTube and Netflix, and it operates with mpv through Lua scripts..

Having this feature on Android would make scrubbing through videos much easier.

Thanks! 🙏