Transform the Type in hana::type

Consider a convenience function to perform operations modifying the contained type in a `hana::type` without unwrapping it and wrapping it again. Consider the following example:

```cpp
// Current method
decltype(hana::typeid_(hana::back(std::declval()))){};

// More expressive
type_transform(some_tuple_type{}, hana::back);
```

Note: It's important that it strips qualifiers since many functions possibly return references.

Possible Implementation (as discussed in Gitter):
```cpp
template
constexpr auto type_transform(hana::basic_type, F f) {
return decltype(hana::typeid_(f(std::declval()))){};
}
```

Start with hana::basic_type and hana::typeid_, then compare the proposed type_transform signature with the current unwrapping and rewrapping example. Check how returned references and other qualifiers are represented, and define completion as a convenience operation that applies the callable to the contained type while stripping qualifiers.

Written by the indexing model from the issue text.