Triggers panel: support both alert list and table-like layouts

[alexanderzobnin]

I get a lot of questions and requests related to table-like layout for triggers panel after latest design update. So I decided to revisit a triggers panel and not just add support for old table layout, but totally update it and add new useful features. Layout similar to alert list panel still supported, so now it's possible to choose what you want. Panel was renamed to Problems panel as well.
The main goal of new design is to combine compact table layout with extended problem info on demand.

[heyrod]

Hi Aleksandr. Can you include in the documentation what icons in the alert panel mean? I guess they correlate with trigger properties in Zabbix but their explanation for Grafana users (not quite familiar with Zabbix) would be helpful.

[alexanderzobnin]

@heyrod Yes, sure. The docs is a part I have to sacrifice sometimes for features 😢