[clang] [clang][Sema] Use original template pattern when declaring implicit deduction guides for nested template classes (PR #68379)

[Paul Kirth via cfe-commits]

ilovepi wrote:

I think your analysis and approach sounds correct, but probably worth checking with someone a bit more familiar with all of the C++ nuance here.

https://github.com/llvm/llvm-project/pull/68379