Change notification history order to sort by date
Reasoning
When viewing history, it makes more sense to see the most recent items first, unlike the old mode where it sorted it by type and urgency.
I've been running this on my desktop and it has been wonderful to not have to scroll so much through history just to get to what I want. I can't get any good side-by-side examples due to restarting plasmashell wiping history, but the screenshots below give a good example.
A user suggested that this would be a config option, but I disagree. I can't imagine a usecase where someone prefers to have it sorted in the old way (especially since it's not even possible to gauge the urgency of notifications in the history currently).
Comparisons
Sorted by type/urgency
This is a great example of how egregiously bad it is, the Dolphin notification happened seven hours ago and the NeoChat ones are shoved all the way down to the bottom.
Sorted by date
This is what I expect, where the notifications appear in the history as the order that they come in. Did I just miss that mail notification? Well, it's right at the top!
Possible side-effects
This is a one-line change, so I can't imagine much. Luckily the C++ backend already supports this, and I've been running this patch for weeks now without any notable issues.