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

[Julian Schmidt via cfe-commits]

5chmidti wrote:

No worries. Feel free to ask in reviews or in discord though. Feel free to close it if you don't want to work on this anymore. The pr will still be linked in the issue, in case someone wants to look at it.

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