feat: New Core/ library (#1975)

Moves everything Camera related into `core/` / `Core/` so that it is better encapsulated from React Native.

Benefits:

1. Code is much better organized. Should be easier for collaborators now, and cleaner codebase for me.
2. Locking is fully atomically as you can now only configure the session through a lock/Mutex which is batch-overridable
    * On iOS, this makes Camera startup time **MUCH** faster, I measured speedups from **1.5 seconds** to only **240 milliseconds** since we only lock/commit once! 🚀 
    * On Android, this fixes a few out-of-sync/concurrency issues like "Capture Request contains unconfigured Input/Output Surface!" since it is now a single lock-operation! 💪 
3. It is easier to integrate VisionCamera outside of React Native (e.g. Native iOS Apps, NativeScript, Flutter, etc)

With this PR, VisionCamera V3 is up to **7x** faster than V2

package/ios/Core/CameraSession+Audio.swift

@@ -0,0 +1,93 @@
+//
+//  CameraSession+Audio.swift
+//  VisionCamera
+//
+//  Created by Marc Rousavy on 11.10.23.
+//  Copyright © 2023 mrousavy. All rights reserved.
+//
+
+import AVFoundation
+import Foundation
+
+extension CameraSession {
+  /**
+   Configures the Audio session and activates it. If the session was active it will shortly be deactivated before configuration.
+
+   The Audio Session will be configured to allow background music, haptics (vibrations) and system sound playback while recording.
+   Background audio is allowed to play on speakers or bluetooth speakers.
+   */
+  final func activateAudioSession() throws {
+    ReactLogger.log(level: .info, message: "Activating Audio Session...")
+
+    do {
+      let audioSession = AVAudioSession.sharedInstance()
+
+      try audioSession.updateCategory(AVAudioSession.Category.playAndRecord,
+                                      options: [.mixWithOthers,
+                                                .allowBluetoothA2DP,
+                                                .defaultToSpeaker,
+                                                .allowAirPlay])
+
+      if #available(iOS 14.5, *) {
+        // prevents the audio session from being interrupted by a phone call
+        try audioSession.setPrefersNoInterruptionsFromSystemAlerts(true)
+      }
+
+      if #available(iOS 13.0, *) {
+        // allow system sounds (notifications, calls, music) to play while recording
+        try audioSession.setAllowHapticsAndSystemSoundsDuringRecording(true)
+      }
+
+      audioCaptureSession.startRunning()
+    } catch let error as NSError {
+      ReactLogger.log(level: .error, message: "Failed to activate audio session! Error \(error.code): \(error.description)")
+      switch error.code {
+      case 561_017_449:
+        throw CameraError.session(.audioInUseByOtherApp)
+      default:
+        throw CameraError.session(.audioSessionFailedToActivate)
+      }
+    }
+  }
+
+  final func deactivateAudioSession() {
+    ReactLogger.log(level: .info, message: "Deactivating Audio Session...")
+
+    audioCaptureSession.stopRunning()
+  }
+
+  @objc
+  func audioSessionInterrupted(notification: Notification) {
+    ReactLogger.log(level: .error, message: "Audio Session Interruption Notification!")
+    guard let userInfo = notification.userInfo,
+          let typeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
+          let type = AVAudioSession.InterruptionType(rawValue: typeValue) else {
+      return
+    }
+
+    // TODO: Add JS-Event for Audio Session interruptions?
+    switch type {
+    case .began:
+      // Something interrupted our Audio Session, stop recording audio.
+      ReactLogger.log(level: .error, message: "The Audio Session was interrupted!")
+    case .ended:
+      ReactLogger.log(level: .info, message: "The Audio Session interruption has ended.")
+      guard let optionsValue = userInfo[AVAudioSessionInterruptionOptionKey] as? UInt else { return }
+      let options = AVAudioSession.InterruptionOptions(rawValue: optionsValue)
+      if options.contains(.shouldResume) {
+        // Try resuming if possible
+        if isRecording {
+          CameraQueues.audioQueue.async {
+            ReactLogger.log(level: .info, message: "Resuming interrupted Audio Session...")
+            // restart audio session because interruption is over
+            try? self.activateAudioSession()
+          }
+        }
+      } else {
+        ReactLogger.log(level: .error, message: "Cannot resume interrupted Audio Session!")
+      }
+    @unknown default:
+      ()
+    }
+  }
+}