Add variable playback speed feature for voice messages

Add playback speed control for voice messages with support for 0.5×, 1×, 1.5×, and 2× playback speeds. The speed button is displayed above the timestamp and cycles through the available speeds when tapped.

libraries/voiceplayer/api/src/main/kotlin/io/element/android/libraries/voiceplayer/api/VoiceMessageEvents.kt

@@ -10,4 +10,5 @@ package io.element.android.libraries.voiceplayer.api
 sealed interface VoiceMessageEvents {
     data object PlayPause : VoiceMessageEvents
     data class Seek(val percentage: Float) : VoiceMessageEvents
+    data object ChangePlaybackSpeed : VoiceMessageEvents
 }

libraries/voiceplayer/api/src/main/kotlin/io/element/android/libraries/voiceplayer/api/VoiceMessageState.kt

@@ -12,6 +12,7 @@ data class VoiceMessageState(
     val progress: Float,
     val time: String,
     val showCursor: Boolean,
+    val playbackSpeed: Float,
     val eventSink: (event: VoiceMessageEvents) -> Unit,
 ) {
     enum class Button {

libraries/voiceplayer/api/src/main/kotlin/io/element/android/libraries/voiceplayer/api/VoiceMessageStateProvider.kt

@@ -47,10 +47,12 @@ fun aVoiceMessageState(
     progress: Float = 0f,
     time: String = "1:00",
     showCursor: Boolean = false,
+    playbackSpeed: Float = 1.0f,
 ) = VoiceMessageState(
     button = button,
     progress = progress,
     time = time,
     showCursor = showCursor,
+    playbackSpeed = playbackSpeed,
     eventSink = {},
 )