Req. normalized arbitrary integer elements

[oscbyspro]

Idea: generic algorithms would never need to perform conservative normalization checks or transformations in big integer branches if big integers are required to offer normalized elements. InfiniInt<T> already does this because it would be silly to do otherwise, but generic algorithms cannot yet assume it.

[oscbyspro]

BinaryInteger/isZero was the first use case I thought of, but I suppose I could improve it be checking the appendix bit first and performing the comparison backwards. I'm sure there are other use cases, however.

Edit: I suppose BinaryInteger/isZero would still improve somewhat since it would compare zero elements instead of one or zero elements (backwards). At the same time, big integers are kind of slow by definition so I would not put much emphasis on an element comparison.

[oscbyspro]

Another unnecessary normalization is found in BinaryInteger.random(in:using:)'s arbitrary integer path, more specifically in one of the internal Randomness algorithms.

[oscbyspro]

My primary concern is that normalized elements may not be normalized after you reinterpret them, which this project does a lot. It could be surprising if elements and elements-as-type behave differently. Also, the performance improvement is small.