[camera_avfoundation] Wrappers swift migration - part 6

[RobertOdrowaz]

Migrates camera wrappers as part of flutter/flutter#119109

This (last wrappers related 🎉) PR migrates wrappers to Swift:

• FLTSavePhotoDelegate
• FLTWritableData
• FLTImageStreamHandler
• CameraProperties
• QueueUtils

In line with Swift conventions, the FLT prefixes are removed.

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

[gemini-code-assist]

Code Review

This pull request continues the migration of the camera_avfoundation plugin from Objective-C to Swift, focusing on several wrapper and utility classes like FLTSavePhotoDelegate, FLTWritableData, FLTImageStreamHandler, CameraProperties, and QueueUtils. The migration is well-executed, adhering to Swift conventions by removing the 'FLT' prefixes and adopting modern Swift patterns.

My review includes a few suggestions:

• A potential bug in SavePhotoDelegate where a nil photo data case is not handled, leading to a false success report.
• A correction for misleading documentation in SavePhotoDelegate.swift.
• A recommendation to use preconditionFailure instead of assertionFailure in CameraProperties.swift for a known invalid input to ensure robustness in release builds.

[RobertOdrowaz]

@hellohuanlin You can take a look again (I've resolved the nit and responded to the rest of the comments)