add Top 5 / Flop 5 securities widget

[mierin12]

Closes #656
Issue https://forum.portfolio-performance.info/t/gewinner-verlierer-liste/27079
Issue https://forum.portfolio-performance.info/t/auswertung-performance-top-contributors-in-desktop-anwendung/27812

Hello,
This is a proposition to add a Top/Flop widge with TWR, TWR annualized, IRR or Abs Perf as performance metrics. I have taken some structures from the recent dividend widget and a bit of Claude help.

Examples from kommer file :

I have added a "subtitle" showing if the selection option is Winner or Loser and the performance metric chosen, I think it gives a clearer view than if it is on the tooltip only.
I have one issue with this subtitle : if the widget is created on a small column, the long text does not appear fully. It does appear fully on several lines on widget update.
Another thing, maybe a detail, it might give the feeling that a right click on this bold subtitle it can open the context menu to change the widget options, but only a right click on the title can do that (in general, would it make sense to extend this right click action to the whole widget, and not only the titles ? Not for chart widget, but for all the other ?).

I was unsure if the 5 limit should be hardcoded or user selectable (do they want a Top 3 ?).

I was also unsure of the name to give. I like Top Flop (and it is still in the code file name) but I was a bit afraid of the accuracy of the translation of such short words. And maybe it would be too informal ? So in the end I followed the "Gewinner-/Verlierer-Liste" found in the forum, but as always with naming I am never sure of myself.

[buchen]

Nice. Let me have a look at it - hopefully over the weekend - I have a similar widget in the mobile application but never came around to porting it to the desktop application. Ideally we use the same concept (and keys) then one can define on the desktop and use on the mobile.