Block casting to an interface marked ComInterfaceType.InterfaceIsIInspectable

[jkoritzinsky]

During the cast path, nothing checks if an interface is an IInspectable interface. This PR adds that check to ensure that we block usage of ComInterfaceType.InterfaceIsIInspectable now that WinRT support is removed.

Fixes #41621

[ghost]

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[jkoritzinsky]

@AaronRobinsonMSFT I'm assuming we want to backport this to 5.0 once this merges into master?

[AaronRobinsonMSFT]

@jkoritzinsky Bah. Boo... I forgot the main branch is now 6. It would be nice if you could try and take it to ship room. Just the product change nothing else. I really consider this a missed scenario for our WinRT in .NET 5.0 plans. It isn't blocking anyone, but shutting down all those entry points would be ideal.

/cc @jeffschwMSFT @Scottj1s

[jkoritzinsky]

The only failure is on Mono WASM and this code only runs on Windows on CoreCLR. I'm going to merge this in.

[jkoritzinsky]

/backport to release/5.0

[github-actions]

Started backporting to release/5.0: https://github.com/dotnet/runtime/actions/runs/234983966