[clang] [clang/AST] Make it possible to use SwiftAttr in type context (PR #108631)

[Pavel Yaskevich via cfe-commits]

xedin wrote:

I think if `noderef` attribute instantiations in your example are considered unique when they appear in different spots then we should have two distinct attributed types but it sounds like both of `noderef` should have one `Attr *` instantiation...

https://github.com/llvm/llvm-project/pull/108631