[clang] [clang] Represent array refs as `TemplateArgument::Declaration` (PR #80050)

[Erich Keane via cfe-commits]

erichkeane wrote:

> @AaronBallman @zygoloid There probably is a missing ODR-use marking somewhere, if you have a clue [#78041 (comment)](https://github.com/llvm/llvm-project/pull/78041#issuecomment-1917571069)
> 
> Alas we do not seem to have a repro for the chromium-reported issue which make debugging it difficult.

*SMH*

https://github.com/llvm/llvm-project/pull/80050