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

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cor3ntin wrote:

@AaronBallman @zygoloid 
There probably is a missing ODR-use marking somewhere, if you have a clue
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.

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