Enable non-default stream

[lubomir]

We have a product that has non-modular package depending on a non-default stream. The instructions for the product tell users they need to manually enable the module stream before installation of the package.

When running fus, this information is not available, so there are dependency problems reported.

Example situation:
repo-1: foo package Requires: bar
lookaside-1: bar:non-default module with bar package

It would be nice to have some way to tell fus that bar:non-default will always be enabled.

CC @contyk for more ideas

[lubomir]

A possible solution here might be to add a new input repo with modulemd metadata only that would contain defaults definition for the module that should be fake enabled. It's a horrible hack, and it will probably break horribly if we try do this for multiple streams of the same module or create some other conflict in this way. But it might work for the simplest cases.