Need benchmark that compares `ebd::unique_fn` with `std::move_only_function` in GCC/Clang/MSVC

[Kim-J-Smith]

More benchmark in different platforms with different compilers is needed.

GCC (libstdc++)

• ebd::unique_fn VS std::move_only_function
• ebd::fn VS std::copyable_function
• ebd::fn_ref VS std::function_ref

Clang (libc++)

• ebd::unique_fn VS std::move_only_function
• ebd::fn VS std::copyable_function
• ebd::fn_ref VS std::function_ref

MSVC (MSVC STL)

• ebd::unique_fn VS std::move_only_function
• ebd::fn VS std::copyable_function
• ebd::fn_ref VS std::function_ref

[Kim-J-Smith]

#73 (comment)