Support for net8.0-ios targets

[kiddkaffeine]

While legacy Xamarin targets do, net7.0-ios and net8.0-ios targets do not currently work with FNA. This is because modern net no longer supports the .dll.config structure.

This has already been solved for desktop targets, but does not correctly handle iOS/tvOS. So in order to fix this, we will need to update FNA's DllMapper to correctly support iOS targets.

Also, symbol stripping behavior appears to have changed and/or does not match the documentation which causes further problems; we've reached out to the dotnet team about this.

[TheSpydog]

I have made the necessary changes to FNADllMap, and I've written up a draft of the documentation for the net8.0 iOS/tvOS workflow. Remaining tasks include:

• Write the section on profiling (I just pointed to the official .NET page on profiling iOS/tvOS apps)
• Test the workflow on tvOS

[TheSpydog]

Docs have been updated!