[camera_avfoundation] Fixes crash when using ResolutionPreset.max with iPhone 17

[LouiseHsu]

Fixes flutter/flutter#175828

The iPhone 17 family's new camera supports a new pixel format, btp2, which is a lossy, compressed format. At 12MP+ resolutions, AVFoundation drops support for standard YUV/BGRA and strictly outputs this format (e.g., 1651798066 / btp2). The engine renderer expects raw pixels and crashes immediately when given this compressed format. (relevant engine issue: flutter/flutter#182908)

Separately, Centre Stage was introduced for iPhone 17 which is a square sensor. A side effect of this is when we request the highest non-btp resolutions, we previously selected based off total number of pixels. This meant that it was returning a wonky 4032x4032 square. I added a check to only return 4:3 resolutions that aren't square like it did previously, just to avoid previous implementations looking weird.

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 under[^1].
• 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 under[^1].
• 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 under[^1].
• All existing and new tests are passing.

[LouiseHsu]

i needed to add this to compile

[gemini-code-assist]

Code Review

This pull request addresses a critical crash when using ResolutionPreset.max with newer iPhone models that output btp2 pixel format, which the Flutter engine cannot render. It also resolves an issue where ResolutionPreset.max could return a square resolution due to Centre Stage camera changes. The changes introduce filtering for unsupported pixel formats and non-4:3 aspect ratios, ensuring a stable and expected camera output. New test cases have been added to validate this behavior.

[gemini-code-assist]

The comment states "Finds the highest available resolution 16:9", but the implementation filters for a 4:3 aspect ratio (is4x3 = abs(ratio - 4.0 / 3.0) < 0.05). Please update the comment to accurately reflect the 4:3 aspect ratio filtering.

Suggested change

	/// Finds the highest available resolution 16:9 in terms of pixel count for the given device.
	/// Finds the highest available resolution 4:3 in terms of pixel count for the given device.

[gemini-code-assist]

The unsupportedSubTypes array is currently defined inside the highestResolutionFormat function. While its scope is limited to this function, defining it as a static let constant outside the function would prevent its re-initialization on every call to highestResolutionFormat, improving minor efficiency and making it clear that these are globally unsupported types for the Flutter Metal renderer.

Suggested change

	// Apple's lossy compressed formats that Flutter Metal can't render.
	let unsupportedSubTypes: [FourCharCode] = [
	1_651_798_066 // Hex for 'btp2', or kCVPixelFormatType_96VersatileBayerPacked12
	]
	static let unsupportedSubTypes: [FourCharCode] = [
	1_651_798_066 // Hex for 'btp2', or kCVPixelFormatType_96VersatileBayerPacked12
	]
	// Apple's lossy compressed formats that Flutter Metal can't render.