Modernized look for context menus on Windows 11

Summary is a little vague; The new Windows 11 context menus are curved and ours are not, and we also don't have the new drop shadows.

Images attached are comparing Qt context menus and notepad context menus. Note the gratuitous amount of shadow in the notepad images.

Additionally noticed after the fact is that our text color doesn't change during hover, while in native apps the text color changes to white!
And the descenders on characters extend 1 pixel outside the highlight in Qt applications which doesn't looks very good.