Work towards shared generics support in IDynamicIntefaceCastable

[MichalStrehovsky]

This is enough to get all our test to pass.

The rest is tracked in dotnet/runtime#72909.

It's a bunch of work and at this point I don't know how much we need it.

[jkotas]

It's unclear to me if anyone uses IDynIntfCast with generics.

I think cswinrt is going to use it with generics. However, I am not sure whether it is going to hit this specific case with missing context.

[MichalStrehovsky]

I think cswinrt is going to use it with generics. However, I am not sure whether it is going to hit this specific case with missing context.

I tried CsWinRT but at this point it's AOT unfriendly beyond any workarounds.

One thing is all the MakeGenericType and MakeGenericMethod calls and string concatenations passed to GetType. Those can be worked around with RD.XML. It's not pretty but it's workable.

But then there's "declaring a delegate type requires writing a whole new line in C# so let's ask Expressions to reflection-emit a new delegate type at runtime for us instead".

I miss MCG.

[MichalStrehovsky]

Let's not merge yet, there's a bug.

[AaronRobinsonMSFT]

I miss MCG.

Said no one ever :-)