[clang] [Sema] Add -Wc++11-narrowing-const-reference (PR #76094)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

I wanted to mention that it is critical to have an incremental path to introduce these warnings for our release process at Google.

I hope this is in line with Clang's needs and not too disturbing to the upstream development. It also helps people with similar needs, i.e. those who want to have warning-clean code and use new versions of Clang as they become available, without waiting to clean up the codebase from new warnings, which may be a costly process.

https://github.com/llvm/llvm-project/pull/76094