[clang-tools-extra] [clang-tidy] Add a new check 'performance-string-view-conversions' (PR #174288)

[Piotr Zegar via cfe-commits]

https://github.com/PiotrZSL commented:

I'm not sure about name, as this is more about unnecessary std::string constructions than std::string_view. Maybe something like performance-redundant-string-construction or something like that.
Idea is good, I would personally remove most of comments, as they only make code less readable.

https://github.com/llvm/llvm-project/pull/174288