[camera_avfoundation] Implementation swift migration - part 6

[RobertOdrowaz]

Migrates camera implementation as part of flutter/flutter#119109

This PR migrates the 3rd chunk of FLTCam class to Swift:

• minimumExposureOffset, maximumExposureOffset, minimumAvailableZoomFactor, maximumAvailableZoomFactor
• pauseVideoRecording, resumeVideoRecording, pausePreview, resumePreview
• setDeviceOrientation, lockCaptureOrientation, unlockCaptureOrientation

Some properties of the FLTCam have to be temporarily made public so that they are accessible in DefaultCamera.

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
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• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under¹.
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• I updated/added any relevant documentation (doc comments with ///).
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Footnotes

1. Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩² ↩³

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[RobertOdrowaz]

Regarding the CLA - I had a typo in my email in commit signatures

[hellohuanlin]

Please don't add autosubmit label until AFTER it's approved AND you want to land it. Sometimes I approve a PR with additional nits.