[Feature Request] DVD-Player core

A dedicated DVD-Player core that should specialize in DVD playback.

Features:

• support playing redump.org style DVD dumps
• read from iso/chd files with m3u playlist support
• full menu support
• chapter support
• fast main menu option, if enabled jump to the main menu directly at start if possible
• allow user to specify a preferred language
• allow subtitles to be rendered semi transparent
• switching audio/subtitle tracks
• subtitle support
• closed caption support (not the same as subtitles)
• angles support, some DVDs may have multiple angles
• auto de-interlace
• save-state support, save the current playback position (maybe the last I-frame ?), selected audio/subtitle tracks etc.
• crop border (8px ?) to remove pixel junk
• able to play DVD games e.g. Dragon's Lair, Scene It?, https://www.mobygames.com/platform/dvd-player/

Have context sensitive inputs depending on if navigation the menu or playing a video.

Button mapping (when playing):
LT/RT: do fancy RW/FF that bases the speed on the analogue value, only as long as the button is being pressed
L1/R1: previous/next chapter
L3/R3: previous/next angle
LEFT/RIGHT: change audio track
UP/DOWN: change subtitle track
START: pause/resume
SELECT: back to menu

Maybe using these?
libdvdread, libdvdnav, libdvdcss

I think this would be a great addition to RetroArch so we can keep perfect copies of our favorite DVDs right beside our retro games.
And being able to play those DVD-Player games in RetroArch would be great.

EDIT:
A simple OSD would be a nice touch as well, maybe a list for each of audio/subtitle tracks, chapters, and angles.
The lists could be like tabs with the LEFT/RIGHT buttons to change between them.
Color for OSD text should be a configurable core option with maybe a nice retro looking green as default.

Button mapping (OSD):
UP/DOWN: navigate current list by one element up/down, with wrap around
LEFT/RIGHT: change current list, previous/next list
OK: change based on current list and selection
CANCEL: hide OSD
Y: toggle simple OSD with current playback information e.g. position, total length, current chapter, etc.
X: toggle simple OSD to change tracks, etc.

No source files, tests, or entry points are named. Start by reviewing RetroArch's core architecture and investigating libdvdread, libdvdnav, and libdvdcss alongside ISO/CHD and m3u handling. Done would require a dedicated DVD-player core covering playback, menus, tracks, subtitles, chapters, angles, input mappings, OSD, and save states.