[clang-tools-extra] [clang-tidy][NFC] Fix a couple of suspicious StringRef::data() usages (PR #158480)

[via cfe-commits]

capitan-davide wrote:

> LGTM But there are still some violations left?

Yes, two more. Unfortunately, they require some refactoring as `llvm::yaml::IO` API uses C-strings only.

```sh
clang-tools-extra/clang-tidy/ClangTidyOptions.cpp:102:36: warning: result of a `data()` call may not be null terminated, provide size information to the callee to prevent potential issues [bugprone-suspicious-stringview-data-usage]
  102 |       IO.preflightKey(Option.first.data(), true, false, UseDefault, SaveInfo);
      |                       ~~~~~~~~~~~~~^~~~
clang-tools-extra/clang-tidy/ClangTidyOptions.cpp:119:28: warning: result of a `data()` call may not be null terminated, provide size information to the callee to prevent potential issues [bugprone-suspicious-stringview-data-usage]
  119 |         IO.mapRequired(Key.data(), Val[Key].Value);
      |                        ~~~~^~~~
```

https://github.com/llvm/llvm-project/pull/158480