Fix memory leak by changing now playing artwork request handler

[MarcelStommel]

Description of Change

Changes the request handler for the now playing artwork to only capture the actual url string. This breaks a reference cycle with MPNowPlayingInfo and MPMediaItemArtwork where MPMediaItemArtwork keeps itself alive through the request handler delegate capturing the whole media element which holds their handler, holding the Metadata class, holding MPNowPlayingInfo, which finally holds MPMediaItemArtwork again. I did not add a test, since the changes are minimal, just changing how the artwork url is captured to avid the reference cycle.

Linked Issues

• Fixes [BUG] Media Element cannot be disconnected #2388

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

[Copilot]

Pull request overview

This PR fixes a memory leak in the MediaElement component on iOS/macOS by refactoring how the now playing artwork request handler is managed. The memory leak occurred due to a reference cycle where MPMediaItemArtwork captured the mediaElement instance through its request handler delegate, while the Metadata class holding the MPMediaItemArtwork was itself referenced by the media element.

Changes:

• Introduced a new RequestHandlerProxy class that captures only the artwork URL string instead of the entire media element object
• Added CoreGraphics using directive for the CGSize type
• Refactored the artwork request handler to use the proxy class method reference instead of a lambda

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[ne0rrmatrix]

Ty for the PR. Good catch. I have tested this in the simulator and I see no issues with this.