[clang] Fix incorrect array initialization with string literal (fixes #112189) (PR #156846)

[via cfe-commits]

awson wrote:

@zygoloid, should I pursue the idea to restrict cloning of subexpressions in `updateStringLiteralType` to the dependent case only?

My current understanding is that the dependency information is completely lost in the `TemplateDeclInstantiator::VisitVarDecl` and never recovered later down the callstack.

https://github.com/llvm/llvm-project/pull/156846