The "Subscribe to more streams" widget has always had this tension
between "Subscribe" vs. "Create" in a way that felt like whatever we
wrote could be confusing. To address this, we enhance the component to
advertise whether additional existing streams that the user can
subscribe to actually exist or not.
- When the user has N>0 streams they can subscribe to, we display
"Browse N more streams".
- When the user has no streams they can subscribe to (i.e. they're
already susbcribed to all the ones they could join) but the user has
permission to create streams, we show a "Create a stream" link.
- If the user doesn't have permission to subscribe to or create any
streams, we don't show a link at all.
Fixes#21865.
Co-authored-by: Jai soni <jai_s@me.iitr.ac.in>