[clang-tools-extra] [clang-tidy] Improve `container-data-pointer` check to use `c_str()` (PR #71304)

[Julian Schmidt via cfe-commits]

https://github.com/5chmidti commented:

@neoncube2 do you plan to continue working on this?

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Because we are emitting a fix-it, it might be a good idea to check if the return type of `c_str` is that of `data` (~possibly unwrapping aliases).

https://github.com/llvm/llvm-project/pull/71304