Missing support for provenance elements

[ThomasJejkal]

It seems that provenance elements defined in the RO-Crate specification are not supported. Thus, it is not possible to describe the provenance of data, e.g., CreateAction, UpdateAction, used instruments etc.

[Pfeil]

Has already been fixed in b196663. I think it should have been possible in beforehand, but with more fiddling, as there was no helper class or builder. The fix is a good idea. Probably, the test / usage example could look more ergonomic (more consistent regarding other builders). I will let the issue open until I was able to take a closer look.