Automatic refresh rate switching setting (#382)

Adds an advanced playback setting to enable automatic refresh rate
switching during playback

When enabled, the app looks at the available display modes, chooses the
best candidate, and attempts to switch to it. After playback ends, the
display is switched back to the original mode.

Closes #62
Closes #379

DEVELOPMENT.md

@@ -49,3 +49,18 @@ You can build the module on MacOS or Linux with the [`build_ffmpeg_decoder.sh`](
 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.
+
+### App settings
+
+App settings are available with the `AppPreferences` object and defined by different `AppPreference` objects (note the `s` differences).
+
+The `AppPreference` objects are used to create the UI for configuring settings using the composable functions in `com.github.damontecres.wholphin.ui.preferences`.
+
+#### How to add a new app setting
+
+1. Add entry in `WholphinDataStore.proto` & build to generate classes
+2. Add new `AppPreference` object in `AppPreference.kt`
+3. Add new object to a `PreferenceGroup` (listed in `AppPreference.kt`)
+4. Update `AppPreferencesSerializer` to set the default value for new installs
+5. If needed, update `AppUpgradeHandler` to set the default value for app upgrades
+    - Since preferences use proto3, the [default values](https://protobuf.dev/programming-guides/proto3/#default) are zero, false, or the first enum, so only need this step if the default value is different