feat(player): demux direct-played containers with ffmpeg on Android

Direct play on Android kept accumulating container patches: AVI with
XviD packed-bitstream timestamps and missing VOL csd played broken,
ASF/WMV and MPEG-PS/VOB had no media3 extractor at all, and MKV needed
a custom extractor stack for zlib-compressed subtitles, LOAS/LATM
audio, cueless seeking, and font attachments.

Demux progressive containers with libavformat behind media3's
extractor API. An AVIO bridge serves libavformat from the
ExtractorInput: every position divergence defers into a RESULT_SEEK
round trip, header reads replay from a block cache while
avformat_open_input restarts, and avformat_seek_file executes seeks
with bounded loader round trips. Packets feed media3's TrackOutputs,
so decoders, passthrough carriers, Dolby Vision RPU/EL conversion
(dvh1 codecs string surfaced from DOVI side data), and the subtitle
pipeline are untouched: embedded fonts feed AssHandler over JNI, ASS
reaches libass as per-sample dialogue, SRT/VTT render as cues, VobSub
maps through media3's VobsubParser, and LOAS/LATM AAC unwraps via
LatmTrackOutput.

Under the default Auto preference FFmpeg demuxes AVI, ASF/WMV,
MPEG-PS, and Matroska/WebM and sits behind media3's list as an
any-container fallback; MP4/TS keep media3's extractors. A playback
setting exposes auto / FFmpeg first / media3 only, and the JNI
load-failure path falls back to stock media3. The custom Matroska
extractor stack and its reflection keeps are retired.

Verified on Pixel 7 (API 36), Box R 4K Plus TV (API 34), and SHIELD
TV (API 30): instrumentation playback suites, the minified R8
reachability gate, and an on-device container matrix with forward and
backward seek landings plus visual subtitle checks.

close #2052

android/app/src/main/cpp/CMakeLists.txt

@@ -19,20 +19,22 @@ else()
     target_link_libraries(dovi_bridge log)
 endif()
 
-foreach(ffmpeg_library avcodec avutil swresample)
+foreach(ffmpeg_library avcodec avformat avutil swresample)
     add_library(${ffmpeg_library} SHARED IMPORTED)
     set_target_properties(${ffmpeg_library} PROPERTIES
         IMPORTED_LOCATION "${MPV_FFMPEG_ROOT}/native/${ANDROID_ABI}/lib${ffmpeg_library}.so")
 endforeach()
 
 add_library(ffmpegJNI SHARED
-    media3_ffmpeg_decoder/ffmpeg_jni.cc)
+    media3_ffmpeg_decoder/ffmpeg_jni.cc
+    media3_ffmpeg_demuxer/ffmpeg_demuxer_jni.cc)
 target_compile_features(ffmpegJNI PRIVATE cxx_std_17)
 target_include_directories(ffmpegJNI PRIVATE
     "${MPV_FFMPEG_ROOT}/include"
     "${CMAKE_CURRENT_SOURCE_DIR}/media3_ffmpeg_decoder")
 target_link_libraries(ffmpegJNI
     avcodec
+    avformat
     avutil
     swresample
     android