[camera_avfoundation] Implementation swift migration - part 3.5

[RobertOdrowaz]

Migrates camera implementation as part of flutter/flutter#119109

This PR consists of everything that was possible to extract from the part 4 which includes:

• Adds audioCaptureDeviceFactory to FLTCamConfiguration.
• Renames the lockCaptureOrientation method of Objective-C type FLTCam when exported to Swift.
• Renames arguments of the captureOutput method of Objective-C type FLTCam when exported to Swift.
• Changes the connection argument type of the captureOutput method of the of FLTCam class to AVCaptureConnection.
• Makes minimum/maximumAvailableZoomFactor and minimum/maximumExposureOffset fields of FLTCam readonly.
• Remove @testable from camera_avfoundation_objc imports

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.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• 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.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or I have commented below to indicate which CHANGELOG exemption this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

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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

[RobertOdrowaz]

@hellohuanlin Please take a look at this when you have some time