[clang] Fix scope of typedefs present inside a template class (PR #146729)

[David Blaikie via cfe-commits]

dwblaikie wrote:

(yeah, it'd be nice if there's a way for this to fall out more naturally, so that dependent typedefs and nondependent ones follow the same codepath)

https://github.com/llvm/llvm-project/pull/146729