[clang][Sema] Fix a crash when instantiating a non-type template argument in a dependent scope.

The type alias template is not diagnosed when instantiating an expected non-type template argument in a dependent scope, causing ICE.

Besides that, the diagnostic message has been updated to account for the fact that the function template  is not the only non-type template.

Fixes #62533

Reviewed By: #clang-language-wg, erichkeane

Differential Revision: https://reviews.llvm.org/D151062