Feat: Improve Publishing DataSource to also work with only the Default stream

[iJungleboy]

I'm submitting a

[x] feature request

...about

[x] admin experience UI
[x] Razor templating
[x] Content Types or data management

Current Behavior / Expected Behavior

The publishing data-source is currently only expected to work, if the in-streams have all the possible variants incl. Draft/Published.

In some cases you want to re-filter the data for publishing after doing other steps, and for that it's not ideal.

So goal is to allow the publishing filter to also work with "Default" only,

Your environment

• 2sxc version(s): 17.10