[clang] [clang-tools-extra] [lldb] [clang] implement CWG1980 and CWG2064: instantiation-dependency improvements (PR #190495)

[Corentin Jabot via cfe-commits]

cor3ntin wrote:

@hubert-reinterpretcast I understand you have opinion on CWG 3179?

https://github.com/llvm/llvm-project/pull/190495