Be able to select agent queue with matrix, similar way as container

[VasiliyNovikov]

Provide a way to select agent queues with matrix the same way as containers described here:
YAML getting started - Containers - With a matrix strategy

Use case - I have .NET Core library that needs to be built and tested on all platforms - Windows, Linux & Mac. Right now I can solve it with Phase templates but I think matrix would be more "natural" and less verbose way to do that

[TingluoHuang]

@VasiliyNovikov it's on our backlog, should be there pretty soon.

We have created a new repository for all YAML related issues, please move the current issue to there.
https://github.com/Microsoft/azure-pipelines-yaml

[VasiliyNovikov]

Moved to here: #4