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

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

Are there any release-notes that should be reverted with this?  or at least modified, since this is reverting stuff?

Also, can you please add the tests/regressions that were found that have lead to this partial revert?

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