Add typed UUID generators

[ivan-kripakov-m10]

Closes #6

[ivan-kripakov-m10]

noticed jacoco failure in CI, took a quick look, the problem is in the not clearly defined API for anyVersion() behaviour (doing so client can tell hegel-core to generate uuid with any version) - currently it can be done via uuids().version(null) - looks a bit awkard

while working on the fix, found hegeldev/hegel-core#140 (comment)

[Liam-DeVoe]

Thanks Ivan! I made a few API changes, otherwise this looks great.

[Liam-DeVoe]

uuids() became typed, would it still make sense to have a separate uuidStrings() generator, or would it be preferable to let clients call toString() on values produced by uuids()?

I prefer the latter, as it results in a more principled API surface

[ivan-kripakov-m10]

I prefer the latter, as it results in a more principled API surface

totally agree, but I anyway decided to be a bit more conservative during making the changes because I wasn't sure about the intuition behind generating uuids as strings in the lib