Add variadic <T1, T2, ...TN> peek()/tap() to FunctionN

[btoo]

Similar to https://github.com/vavr-io/vavr/issues/2723, it would be quite useful to be able to non-disruptively access the values of variadic types (which I'll admit would probably be a larger effort than adding the current peek/tap implementations, all monadic, was)

Function3.of(functionWith3Args)
  .peek(debug3Values)
  .andThen(...)