new: add playback speed control

data/playback/src/commonMain/kotlin/fr/ajaury/gwenedeg/player/data/PlaybackRepositoryImpl.kt

@@ -136,6 +136,10 @@ internal class PlaybackRepositoryImpl(
         audioPlayer.seekTo(position)
     }
 
+    override fun setSpeed(speed: Float) {
+        audioPlayer.setSpeed(speed)
+    }
+
     override fun seekToSentence(sentenceIndex: Int) {
         val matchingSubtitleLine = subtitle.value.lines.getOrNull(sentenceIndex) ?: return
         audioPlayer.seekTo(matchingSubtitleLine.startTime)

data/playback/src/commonMain/kotlin/fr/ajaury/gwenedeg/player/domain/PlaybackRepository.kt

@@ -25,6 +25,8 @@ interface PlaybackRepository {
 
     fun seekTo(position: Duration)
 
+    fun setSpeed(speed: Float)
+
     fun seekToSentence(sentenceIndex: Int)
 
     fun goToPreviousSentence()