Move native builds to wholphin-extensions (#1172)

## Description
This PR moves the native components (ffmpeg decoder, av1 decoder, &
`libmpv`) to https://github.com/damontecres/wholphin-extensions. They
can be retrieved as gradle dependencies now.

This allows for contributors to more easily include these extensions
when building Wholphin locally.

There are no user facing changes in this PR.

Note: the kotlin code for interfacing with `libmpv`, ie `MPVLib` &
`MpvPlayer`, is still in this repo for now.

### Related issues
Related to #828

### Testing
Emulator

## Screenshots
N/A

## AI or LLM usage
None

DEVELOPMENT.md

@@ -43,21 +43,11 @@ Code is split into several packages:
 - `ui` - User interface code and ViewModels
 - `util` - Utility classes and functions
 
-### Native components
+## Extensions
 
-#### FFmpeg decoder module
+Wholphin uses several native components for extra playback compatibility. This includes Media3 ffmpeg/av1 decoders and `libmpv`. These extensions are not required to build the app, but without them some functionality will not work.
 
-Wholphin ships with [media3 ffmpeg decoder module](https://github.com/androidx/media/blob/release/libraries/decoder_ffmpeg/README.md).
-
-It is not required to build the extension in order to build the app locally.
-
-You can build the module on MacOS or Linux with the [`build_ffmpeg_decoder.sh`](./scripts/ffmpeg/build_ffmpeg_decoder.sh) script.
-
-#### MPV player backend
-
-Wholphin has a playback engine that uses [`libmpv`](https://github.com/mpv-player/mpv). The app uses JNI code from [`mpv-android`](https://github.com/mpv-android/mpv-android) and has an implementation of `androidx.media3.common.Player` to swap out for `ExoPlayer`.
-
-See the [build scripts](scripts/mpv/) for details on building this component.
+If you want to include these in a local build, see the [instructions here](https://github.com/damontecres/wholphin-extensions?tab=readme-ov-file#usage) for configuring the repository.
 
 ### App settings