Add Hexagon Kotlin Backend repository

[jaguililla]

Closes #357 and closes hexagontk/hexagon#165

Demo implementation repository: https://github.com/hexagonkt/real_world

[jaguililla]

Hello, I've changed the project since you tagged it as needs review. It is now updated to the latest Hexagon version.

If you need something on my side, or see something that should be improved, please let me know.

Thanks!

[jaguililla]

Does needs review means you still have to review, or is something missing on my side? If it is the latter, please tell me what should I change. Thanks!

[jaguililla]

Can someone give me feedback about this implementation?

More than nine months have passed since it was opened and the only message I got is the needs review tag. What does it mean though? Could you explain me if there is something I should change?

I've checked the PRs and there are many implementations already merged that were filed later than mine. Do you have any sort of priority? and if so, what is the criteria? (it doesn't seem to be a FIFO)

Thank you for your time.