Group-Level Matrix

I may want to perform a series of steps (as parallel jobs) pertaining to a single matrix combination, though at the moment, matrix is only available on a command type step. I would like to be able to represent something like the following as well:

- group: {{matrix}}
    - darwin
    - linux
    - windows
    OS: {{matrix}}
    # Assume these are expensive, yet parallelizable commands.
    - command: parallel-command-1
    - command: parallel-command-2

The desired outcome would be equivalent to two separate groups, though with less duplication of yaml. Also of note is the potential introduction of an env attribute at the group level in the above example.

Hi @kgillette

Thank you for the feedback, we do not have any enhancements planned around matrix this year due to other high priority items. However we have in our backlog to enhance matrix support and we will keep this feedback into consideration.