Media gallery - part 1(#3588)

* Introduce a `MediaEventsTimelineFlowCoordinator`
* Update SDK API and architecture
* Add a feature flag, add translations
* Move the media events timeline presentation under the room flow coordinator state machine
* Rename `TimelineViewState.timelineViewState` of type `TimelineState` to `timelineState`
* Enabled SwiftLint's `trailing_closure` rule and fix the warnings.

ElementX/Sources/Services/Timeline/TimelineItems/Items/Messages/VoiceMessages/VoiceMessageRoomPlaybackView.swift

@@ -61,9 +61,10 @@ struct VoiceMessageRoomPlaybackView: View {
         if let url = playerState.fileURL {
             WaveformView(audioURL: url,
                          configuration: .init(style: .striped(.init(color: .black, width: waveformLineWidth, spacing: waveformLinePadding)),
-                                              verticalScalingFactor: 1.0),
-                         placeholder: { estimatedWaveformView })
-                .progressMask(progress: playerState.progress)
+                                              verticalScalingFactor: 1.0)) {
+                estimatedWaveformView
+            }
+            .progressMask(progress: playerState.progress)
         } else {
             estimatedWaveformView
         }