Group consecutive timeline events (defined as being the same action and operating on the same target) together so that the same target is not seen multiple times in a row. This notably does not completely aggregate all events together, so the timeline may still appear as "A B A" if several instances of event A were broken up by event B. For collapsed groups, we render "and N other user(s)" in the description of the event, with a popover that shows the collapsed users if "N other user(s)" is hovered. The number of events fetched was increased so that `limit` refers to the number of items in the timeline post-grouping. Signed-off-by: Kevin Yap <me@kevinyap.ca>