Span: Add tests to verify type loader checks for ref-like types

[jkotas]

• Span cannot be boxed
• Span cannot be used as argument of generic instantiations
• Span cannot be used as type of static fields or non-value type instance fields

[ahsonkhan]

@kouvel, any updates on this issue?

[kouvel]

I had tested the C# versions of these tests and all is good, just need to convert them to IL tests

[ahsonkhan]

@kouvel, any updates on this issue?
This is one of the two remaining issues under "VM - Correctness" from https://github.com/dotnet/coreclr/issues/5851#issue-160849016

[kouvel]

Nope, haven't had the time to look at my issues

[ahsonkhan]

@kouvel, can you please triage/prioritize this issue. Ty

[ahsonkhan]

Fixed in dotnet/coreclr#15745.
Closing.