[Epic] Use newer/better interop primitives

[mattleibow]

Description

The SkiaSharp codebase is really old and is using many old primitives. Some such things are arrays instead of renting/span or MonoTouch attributes.

This issue is an epic issue to track what we would like. If there is something I missed or some new feature that will improve performance, please add a comment or even open a PR.

Tasks

• Switch to Span<T> or ReadOnlySpan<T> #2616
  https://learn.microsoft.com/en-us/dotnet/standard/memory-and-spans/memory-t-usage-guidelines
• Switch to native function pointers
  https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-9.0/function-pointers
  https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/unsafe-code#function-pointers
• Remove [MonoPInvokeCallback] attributes
• Use Intrinsics where we can/should