`kele-list`: Implement periodic updating

[jinnovation]

Currently, when a user invokes kele-list, the resulting list is largely static. User can invoke a "refresh" w/ g (WIP) but this is obviously still very manual.

Let's implement the ability for kele-list buffers to periodically re-pull and display updates to the search set. The poll interval should be customizable, and users should be able to enable/disable live updating on a buffer-local basis. This would be particularly useful with #137.

Definition of Done

• kele-list can live-update to periodically refetch any changes to the list set
• Users can customize the kele-list refresh interval
• Users can customize default enable/disable behavior for kele-list live updating
• Users can enable/disable live updating on a per-buffer basis

[jinnovation]

Let's hold off on this until #204.