Add an option to start capture manually.

[shogo4405]

Description & motivation

• Added an option to manually start capturing camera and microphone data.
  • This behavior is planned to be the default in the 2.1.x series.
• The main background for this implementation is explained here:
  • AVCaptureMultiCamSession sometimes blocks the main thread during app startup on iOS18.0, iOS18.1... #1637

Usage

let mixer = MediaMixer(
  multiCamSessionEnabled: true, 
  multiTrackAudioMixingEnabled: false,
  // Please set to true. default value is false.
  useManualCapture: true
)

mixer.attachAudio()
mixer.attachVideo()

// Must call startRunning()
mixer.startRunning()

Type of change

• New feature (non-breaking change which adds functionality)

Screenshots: