Alllow rendering group items with group views

Ok, good start.

Now we just need to decide what rows and style options we need.

Basically, the view works, but the result gets reduced to one result, I think somewhere here:
https://git.drupalcode.org/project/commerce_vado/-/blob/2.0.x/src/Plugin...

So basically, the issue was here setting the single group id as an $id_field_alias, was just returning one result, and preventing the array from being built for each result - since there is only one group.

Not sure the most dependable way to get the group_item ids off the view, and also, I think this would require the view to have a group item relationship.

Updated the documentation.