[clang] [clang] require arg list in type specifiers using template kw (PR #94674)

[Erick Velez via cfe-commits]

evelez7 wrote:

I'm also preparing a patch for deprecating the use of template kw without an arg list for alias and class templates. Decided to split that up since a lot of tests require deprecation messages.

https://github.com/llvm/llvm-project/pull/94674