[macOS] Fix hot restart videoCapturer crash
[macOS] Fix hot restart videoCapturer crash

If RTCVideoView with opened _localRenderer placed at root Widget, after hot restarting application was crashed with error:

*** Assertion failure in -[RTCCameraVideoCapturer dealloc], ../../sdk/objc/components/capturer/RTCCameraVideoCapturer.m:113
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Session was still running in RTCCameraVideoCapturer dealloc. Forgot to call stopCapture?'

flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc,flutter-webrtc/flutter-webrtc