[clang-tools-extra] [clang] [clang][NFC] Refactor `CXXNewExpr::InitializationStyle` (re-land) (PR #71417)

[via cfe-commits]

cor3ntin wrote:

Would it be helpful for you if we:

- Introduce `getInitializationStyleAsWritten` and `hasInitializerAsWritten`  methods (that map `Implicit` to `NoInit`)
- Take the opportunity to rename `Call/List` to `Paren/BraceInitialization` ?

https://github.com/llvm/llvm-project/pull/71417