v1.1.0 Callable Concept

Ads these 3 concepts:

• Callable<T>: Anything that looks like a function. https://en.cppreference.com/w/cpp/named_req/Callable.html - Useful when you want to constrain a function argument to anything function with any amount of arguments of any type.
• CallableOfArity<T, unsigned>: Callable & the function takes an exact amount of parameters.
• CallableOfAtLeastArity<T, unsigned>: Callable & the function takes at least the given amount of parameters.