multimedia/jellyfin-ffmpeg7: New port: FFmpeg with patches for HDR tone mapping (tonemapx/libplacebo)

FFmpeg with Jellyfin patches for HDR tone mapping, including the SIMD-optimized
tonemapx filter (libplacebo-based HDR to SDR conversion).

WWW: https://github.com/jellyfin/jellyfin-ffmpeg

PR: 297604