Fix memory leaks in MAUI views

[mattleibow]

Description of Change

It is very easy to create a circular reference in iOS and we had a few. When you have an event from a platform view to another instance that then references that platform view, you get an un-collectable set.

This PR breaks this chain by making the platform view have an event on a proxy object that has a weak reference to handlers and/or virtual views.

Bugs Fixed

• Fixes [BUG] .Net MAUI SKCanvasView memory leak on IOS #2923

API Changes

None.

Behavioral Changes

None.

Required skia PR

None.

PR Checklist

• Has tests (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Merged related skia PRs
• Changes adhere to coding standard
• Updated documentation

[github-actions]

The backport to release/2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release/2.x release/2.x
# Navigate to the new working tree
cd .worktrees/backport-release/2.x
# Create a new branch
git switch --create backport/pr-2955-to-release/2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 ccde024b628e4454dfc713fb3f6f27f071883b79
# Push it to GitHub
git push --set-upstream origin backport/pr-2955-to-release/2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release/2.x

Then, create a pull request where the base branch is release/2.x and the compare/head branch is backport/pr-2955-to-release/2.x.

[albilaga]

@mattleibow this one is only on 3.0.0 right? 2.88 is not possible?

Looks like even in 3.0.0 preview 4 is not available yet.

[mattleibow]

Preview 4 is out 2 months ago: https://www.nuget.org/packages/SkiaSharp/3.0.0-preview.4.1

I am getting ready to push preview 5 out with some extra things.