Add segwit xpub to ku

[jusasiiv]

This adds the option to get ku output also for Bitcoin BIP49 p2sh segwit and BIP84 segwit xPubs

Can be considered if the bipxx_as_string codes would be better in HierarchialKey

[jusasiiv]

Hi,

This will break a lot of tests because it will add output. Go ahead and eyeball the diffs, and if they look okay, I can quickly repair them after I commit your fix

The diff is pretty messy, but I think it looks fine. If you could repair the tests that would be great.