[clang-tools-extra] [clang-tidy] Add more constexpr options to `readability-identifier-naming` (PR #162160)

[Alex White via cfe-commits]

MilkeeyCat wrote:

I'll change Release Notes and add test cases soon, but I can't decide how should the options be called, is it `GlobalConstexprCase` because there's already `GlobalConstantCase`, or is it `GlobalConstexprVariableCase` because there's already `ConstexprVariableCase` or somehow else?

https://github.com/llvm/llvm-project/pull/162160