Fixing: UIHostingController does not automatically resize to hug subviews in iOS 15.0

[sophialee0416]

Platforms Impacted

• iOS
• macOS

Description of changes

Addressing a bug discovered here: #648 (comment)
UIHostingController in iOS 15 does not automatically resize to hug subviews if they are dynamically changing.
Note: The small avatar animation jumps + holes in cutout is a bug separate from this PR and is currently being fixed in #648

Verification

Below are recordings tested in iOS 15, but manual tests in iOS 13 + 14 were performed as well.

Before	After

Pull request checklist

This PR has considered:

• Light and Dark appearances
• VoiceOver and Keyboard Accessibility
• Internationalization and Right to Left layouts
• Different resolutions (1x, 2x, 3x)
• Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)

Microsoft Reviewers: Open in CodeFlow

[mischreiber]

Signing off assuming this was also tested in iOS 13 and 14 simulators!

[sophialee0416]

Signing off assuming this was also tested in iOS 13 and 14 simulators!

Will mention that in the description!

[rdeassis]

Please test this change thoroughly in different device types, orientation changes and iOS versions. We need to be 100% sure that this will not cause an undesired side effect on other controls that are already being used by the client apps.