WIP - implement ChunkedRecorder

- configure AVAssetWriter for fragmented mp4 output
- implement ChunkedRecorder to received chunk data via AVAssetWriterDelegate

package/ios/Core/ChunkedRecorder.swift

@@ -0,0 +1,70 @@
+//
+//  ChunkedRecorder.swift
+//  VisionCamera
+//
+//  Created by Rafael Bastos on 12/07/2024.
+//  Copyright © 2024 mrousavy. All rights reserved.
+//
+
+import Foundation
+import AVFoundation
+
+
+class ChunkedRecorder: NSObject {
+  
+  let outputURL: URL
+  
+  private var initSegment: Data?
+  private var index: Int = 0
+  
+  init(url: URL) throws {
+    outputURL = url
+    
+    guard FileManager.default.fileExists(atPath: outputURL.path) else {
+      throw CameraError.unknown(message: "output directory does not exist at: \(outputURL.path)", cause: nil)
+    }
+  }
+  
+}
+
+extension ChunkedRecorder: AVAssetWriterDelegate {
+  
+  func assetWriter(_ writer: AVAssetWriter, 
+                   didOutputSegmentData segmentData: Data,
+                   segmentType: AVAssetSegmentType,
+                   segmentReport: AVAssetSegmentReport?) {
+    
+    switch segmentType {
+    case .initialization:
+      saveInitSegment(segmentData)
+    case .separable:
+      saveSegment(segmentData)
+    @unknown default:
+      fatalError("Unknown AVAssetSegmentType!")
+    }
+  }
+  
+  private func saveInitSegment(_ data: Data) {     
+    initSegment = data
+  }
+  
+  private func saveSegment(_ data: Data) {
+    guard let initSegment else {
+      print("missing init segment")
+      return
+    }
+    
+    let file = String(format: "%06d.mp4", index)
+    index += 1
+    let url = outputURL.appendingPathComponent(file)
+    
+    do {
+      let outputData = initSegment + data
+      try outputData.write(to: url)
+      print("writing", data.count, "to", url)
+    } catch {
+      print("Error--->", error)
+    }
+  }
+  
+}