Shaman support for exotic floating point types

[cedricchevalier19]

Shaman requires std::is_arithmeticwhich is only fulfilled by std::bfloat16_t since C++23 and more annoyingly cannot be changed on the user side.

https://en.cppreference.com/w/cpp/types/is_floating_point

Checks whether T is a floating-point type. Provides the member constant value which is equal to true, if T is the type float, double, long double, or any extended floating-point types (std::float16_t, std::float32_t, std::float64_t, std::float128_t, or std::bfloat16_t)(since C++23), including any cv-qualified variants. Otherwise, value is equal to false.

The behavior of a program that adds specializations for std::is_floating_point or std::is_floating_point_v is undefined.