[clang] [NFC][analyzer] Remove CheckerNameRef::getName() (PR #130780)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

:thinking: Instead of this change I could also imagine introducing an accurately named explicit method – e.g. `StringRef toStringRef()` – and using that for all `CheckerNameRef` → `StringRef` conversions (including the half dozen cases where the codebase already uses `operator StringRef()` implicitly). 

@steakhal or anybody else: What do you think about this situation? Which would be the more elegant approach: the implicit `operator StringRef()` or the explicit `toStringRef()`?

I would be grateful for a quick review on this PR, because I have several mostly written changes that I will need to refactor depending on this change.

https://github.com/llvm/llvm-project/pull/130780