[camera] Options to scan for physical and/or logical cameras on iOS

[rickcasson]

Based on feedback from @stuartmorgan, I have refactored my original PRs (#5957 and #5958) to not disrupt the existing functionality of the availableDevices method, while still providing the option to access the extended list of iOS cameras (both physical and logical) based on Apple's documentation: https://developer.apple.com/documentation/avfoundation/avcapturedevice/devicetype

This changes hopefully make room to eventually add the ability to access logical cameras on Android (or other?) devices at some point, but the changes on iOS were more pressing for my project so I wanted to at least start there.

I've included external cameras as "physical devices" so this PR should fix the same issue as #5892.

List which issues are fixed by this PR. You must list at least one issue. closes flutter/flutter#134151 closes flutter/flutter#130073 closes flutter/flutter#142025

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[stuartmorgan-g]

Based on feedback from @stuartmorgan, I have refactored my original PRs (#5957 and #5958) to not disrupt the existing functionality of the availableDevices method, while still providing the option to access the extended list of iOS cameras (both physical and logical)

My primary feedback, which continues to be true, is that this needs a full design proposal (https://github.com/flutter/flutter/wiki/Design-Documents). There are many possible ways to handle different device types, and this PR would lock us into a specific one without there having been a discussions of alternatives and the pros and cons of each.

This changes hopefully make room to eventually add the ability to access logical cameras on Android (or other?) devices at some point

If we can't confidently answer the question of whether this API will apply well to other platforms, that's a strong signal that this hasn't gone through sufficient evaluation yet. See https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#platform-support

but the changes on iOS were more pressing for my project so I wanted to at least start there

Our priority is the long term health and usability of the plugin's API surface; our process is designed to support that rather than patchworks of APIs developed in small pieces based on individual contributor deadlines, as cases where the latter has happened the outcomes have often not been good.

[ditman]

I took a quick look at MDN, and I don't think there's a concept of Logical/Physical Cameras in the Web. Cameras (and other types) are just providers of a MediaStream that can be connected to a Canvas or a WebRTC connection.

There's also no "constraint" to select physical from logical cameras. See: MediaTrackConstraints.

(It wouldn't be the first time that the web ignores values from some parameters, though!)

[stuartmorgan-g]

Marking as a draft pending a design document, per comment above.

[goderbauer]

(triage): I am going to close this one since there hasn't been any follow-up. If you find the time to address the feedback given above please reopen this. Thank you.