Rethink events page logic

[beevee]

API returns last month events, sorted by timestamp, 100 events on one page. Frontend groups every single page by metric name (i.e. events related to one metric are shown together). Since this grouping occurs within a single page, same metric can have events on different pages, which confuses users.

Possible solutions:

1. Change server-side logic and API: return pre-grouped events to frontend. This can become inconvenient if one metric generates a lot of events: it will occupy first several pages.
2. Show metric events collapsed on frontend (with only last event or some statistic visible). Show other events after click.