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ARROW-18350: [C++] Use std::to_chars instead of std::to_string (#14666)

`std::to_chars` is locale-independent unlike `std::to_string`; it may also be faster.

This PR does neither bother with test and benchmark files, nor with debug output strings.

Unfortunately, some standard libraries don't provide a full implementation of `std::to_chars`, in which case `std::to_string` is still used for the unimplemented input types.

Authored-by: Antoine Pitrou <antoine@python.org>
Signed-off-by: Antoine Pitrou <antoine@python.org>