Add getCurrentJob and getCurrentScopeJob functions

[recheej]

Resolves #2159 .

Adding different names for the suspend and CoroutineScope extension versions since there can be some confusion. Added docs and did api dump. Also replaced places in the code base (mostly tests) that accessed jobs with !!

[elizarov]

@recheej Can you, please, elaborate what's your use-case for these functions? What kind of code needs them?

[recheej]

@elizarov I personally would use these functions for debugging coroutines code (see state of job, children, etc). But I could also see them being used for lower level coroutines work or for logging state of things.

In the end, I think the Job is such an important context element that it deserves its own function(s).

[qwwdfsad]

Thanks for your contribution!
We've discussed it internally and decided that it's not the addition we are ready to make. It's unclear who and how is going to use it, its naming is misaligned with existing memebrs (e.g. CoroutineScope.coroutineContext, but currentCoroutineContext()).

We'd like to introduce the only coroutineContext.job: Job? extension property for the sake of brevity where it is necessary. If you want to do this extra-mile and replace your PR with that, we'd be happy to help you with review and integration. If not, it's completely okay to tell us, then we are going to implement it ourselves

[recheej]

Sure I can do that change