[clang-tidy] report `performance-prefer-single-char-overloads` for stream insertion

```cpp
#include

void f(int k, int v)
{
std::cout << k << "-" << v << "\n";
}
```

https://godbolt.org/z/Kdssdfxr6

Using a char instead of a string should be faster (even though there is the probably bogus #65040 by myself).