[libc++] `<string>`: `string::resize_and_overwrite` missing _Mandates_

[hewillk]

From [string.capacity]:

Mandates: OP has an integer-like type ([iterator.concept.winc]).

The following should be rejected because bool is not an integer-like type:

#include <string>

int main() {
  std::string s;
  s.resize_and_overwrite(10, [](char*, std::size_t) { return true; });
}

https://godbolt.org/z/YEshcM1P5