Add assume function to abort tests instead of failing them

[evant]

jvm only, uses open4j's TestAbortedException under the hood so works on junit5 or other compatible testing framework (does not work on junit4)

Fixes #432

[evant]

update: I'm worried about fact that this won't work in junit4 projects which is still very common on android unfortunately, will have to think about dealing with this, would documentation be enough?