Make it easier to find the next event if there are no events on today

[kimadactyl]

User story

As someone looking for events in Manchester, I want to see when the next event is on if there are none on today, in order that I don't have to spend ages clicking around hunting for one.

As The Trans Dimension, we want to always show people content, in order that they think the project is still maintained

Acceptance criteria

• If there are no events in the events index for a given selection, it says "go to next event"

Implementation notes & questions

This is a dupe of this feature in PlaceCal: geeksforsocialchange/PlaceCal#2400

Implementation plan

_{Huly®: TD-468}