Update SkiaSharp to the latest stable version (2.88.6)

[mattleibow]

Description of Change

Time to get new things!

[brminnick]

Thanks @mattleibow! Any estimation for when this PR will be released?

As I'm sure you're aware, a security vulnerability was reported on SkiaSharp this weekend. The good news is that the vulnerability is patched in SkiaSharp v2.88.6, the version this PR updates to for .NET MAUI, so the next MAUI release that includes this PR resolves this security vulnerability for .NET MAUI devs!

There's many libraries that use Microsoft.Maui.Graphics.Skia, and the latest stable version of Microsoft.Maui.Graphics.Skia currently uses SkiaSharp v2.88.2 (includes security vulnerability), and the latest preview version of Microsoft.Maui.Graphics.Skia currently uses SkiaSharp v2.88.4-preview.82 (also includes security vulnerability).

The biggest headache I've discovered so far is that tizen-net7.0 library has a transitive dependency to SkiaSharp via net7.0-tizen -> Tizen.UIExtensions.NUI -> Microsoft.Maui.Graphics.Skia -> SkiaSharp. @JoonghyunCho on the Tizen team is aware of it and will be working with his team to bump Tizen.UIExtensions.NUI's dependency to Microsoft.Maui.Graphics.Skia once the new version of Microsoft.Maui.Graphics.Skia containing this PR has been released.

The good news is that we've patched it in CommunityToolkit.Maui by adding a direct dependency to SkiaSharp v2.88.6 for our Tizen builds, and we will be releasing CommunityToolkit.Maui v6.0.0 this week. So any dev who updates to CommunityToolkit.Maui v6.0.0 will by default be using the latest version of SkiaSharp on Tizen, alleviating any potential security vulnerabilities for them. I've also created an Issue to remind us to remove this direct dependency to SkiaSharp once the new version of Microsoft.Maui.Graphics.Skia is released.

tl;dr There's security vulnerability in SkiaSharp, patched in SkiaSharp v2.88.6, and Microsoft.Maui.Graphics.Skia is the long-tail that needs to be patched (done) + released (pending) first before other libraries can fix their transitive vulnerabilities.

[jsuarezruiz]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 3 pipeline(s).

[mattleibow]

/backport to net7.0

[github-actions]

Started backporting to net7.0: https://github.com/dotnet/maui/actions/runs/6302042011

[github-actions]

@mattleibow backporting to net7.0 failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch

Applying: Update SkiaSharp to 2.88.6
.git/rebase-apply/patch:225: trailing whitespace.
			// native library loading logic for the .NET Framework (Visual Studio). 
warning: 1 line adds whitespace errors.
Using index info to reconstruct a base tree...
M	eng/Microsoft.Extensions.targets
M	eng/Versions.props
M	src/Graphics/samples/GraphicsTester.Skia.Mac/GraphicsTester.Skia.Mac.csproj
M	src/SingleProject/Resizetizer/src/ResizetizerPackages.projitems
M	src/SingleProject/Resizetizer/test/UnitTests/Resizetizer.UnitTests.csproj
Falling back to patching base and 3-way merge...
Auto-merging src/SingleProject/Resizetizer/test/UnitTests/Resizetizer.UnitTests.csproj
CONFLICT (content): Merge conflict in src/SingleProject/Resizetizer/test/UnitTests/Resizetizer.UnitTests.csproj
Auto-merging src/SingleProject/Resizetizer/src/ResizetizerPackages.projitems
CONFLICT (content): Merge conflict in src/SingleProject/Resizetizer/src/ResizetizerPackages.projitems
Auto-merging src/Graphics/samples/GraphicsTester.Skia.Mac/GraphicsTester.Skia.Mac.csproj
Auto-merging eng/Versions.props
Auto-merging eng/Microsoft.Extensions.targets
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Update SkiaSharp to 2.88.6
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!

[github-actions]

@mattleibow an error occurred while backporting to net7.0, please check the run log for details!

Error: git am failed, most likely due to a merge conflict.

[mattleibow]

Backport in #17663