Improve the style of the visitor log

[tsteur]

Currently, the visitor doesn't look so much appealing visually, especially the right part which shows all the actions. Plus it shows numbers in front of each action which is not relevant or helping.

Instead we could show the actions more in a "timeline" way also making it more clear the visitor log shows a timeline of all actions. This could be a vertical line on the left part of the list of actions, separated by an icon for each action. To the left of the icon, or on hover we would show instead when the action was performed. This gives a user a much better idea of how much time has passed between each action and lets you better understand the behaviour of a visitor. The time we show could be either the server time, the local time, or the time since the visit started. Because it would be confusing between local vs server time it may be best to show the time passed since visit start.

It could look a little bit like our History page but instead of the red dot we show an icon depending on the action.

This could also work nicely with the new grouping feature we would want to have within the visitor log (#13136) as it would basically show another vertical timeline indented and it would be collapsible.

[tsteur]

example: (not styled at all, not using proper icons, ...)