[camera_windows] Restore image streaming support

[liff]

Restores support for streaming images from the camera(s) in Windows.

I reverted #7951 as a starting point and attempted to resolve the issues that were raised:

• The startImageStream and stopImageStream methods are no longer async.
• There is no global EventSink for the images. Each camera gets a dedicated EventChannel for the image data.

In addition, the images are submitted to the EventChannels from a dedicated hidden window -based task runner, based on flutter/engine#24232.

Implemented with assistance from @jokerttu.

Fixes flutter/flutter#97542.

Pre-launch Checklist

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] I read the Tree Hygiene page, which explains my responsibilities.
• [x] I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages repo does use dart format.)
• [x] I signed the CLA.
• [x] The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• [x] I linked to at least one issue that this PR fixes in the description above.
• [x] I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• [x] I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or this PR is exempt from CHANGELOG changes.
• [x] I updated/added relevant documentation (doc comments with ///).
• [x] I added new tests to check the change I am making, or this PR is test-exempt.
• [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[stuartmorgan-g]

From triage: This was waiting on the streaming support query API, so was blocked on that. I believe it's now unblocked.

[liff]

Rebased on main and added the support query.

[liff]

Attempted to address some of the review issues, will continue with the remaining stuff later.

[stuartmorgan-g]

From triage: @liff Are you still planning on updating this PR based on the review feedback?

[liff]

From triage: @liff Are you still planning on updating this PR based on the review feedback?

Yes—though I don’t know when, I’ve been preoccupied with other stuff lately.

[Piinks]

Thank you for your contribution. I'm going to close this PR for now since there are outstanding comments, just to get this off our PR review queue. Please don't hesitate to re-open or submit a new PR if you have the time to address the review comments. Thanks!