add only-populated option to niri/workspaces module

[hansp27]

When set to true, only workspaces which contain windows will be drawn. (the active one will always be drawn)

[jmickelin]

I would suggest also letting it show explicitly named workspaces, i.e. ones where the "name" attribute is non-null. This way, users can create common workspaces in their config that are always shown, and the dynamically created ones remain hidden until you either put something there or you set a name for them interactively with the set-workspace-name command.

[hansp27]

@jmickelin I rewrote the configuration option to be a string instead of a boolean and added your suggested handling too. You can check it out over at #4001.

Thanks for your suggestion.

[hansp27]

Closing in favor of #4001