uasyncio.queues: Add simple implementation of asynchronous queues for uasyncio

Hi, I've added simple port of asyncio.queues.Queue. It can be a bit slow, but works well for me.
For testing:
```bash
cd uasyncio.queues/tests
micropython test.py
```
Thanks for this unit test. Most "test" files currently spread around micropython-lib are not really formalized tests, but manual tests or even usage examples. Should all those be cleaned up by renaming to have example_*.py naming pattern, so we had a better chance to run an automated testsuite for entire project, what do you think?