Port of Array Inherent Methods

This module ports the inherent methods available on the array fundamental type.

As of 1.56, only .map() is stable. The .as_slice() and .as_mut_slice() methods are ported, as the behavior has always been stable, and only the name is new.

The remaining methods (as of 1.56, .each_mut(), .each_ref(), .zip()) are not ported. While BitArray is capable of implementing their behavior with the existing crate APIs, the const-generic system is not yet able to allow construction of an array whose length is dependent on an associated const in a type parameter.

These methods will not be available until the const-generic system improves enough for bitvec 2 to use the proper BitArray API.