Change the text color when appmenu is selected or hovered

When the mouse hovers the appmenu item, the text color should be inverted to the background
color. Before this commit, the text was still the same color as the "REST" state, making it
difficult to recognize.

applets/appmenu/package/contents/ui/MenuDelegate.qml

@@ -66,5 +66,9 @@ AbstractButton {
 
     contentItem: PC3.Label {
         text: controlRoot.Kirigami.MnemonicData.richTextLabel
+        // Kirigami.Theme.highlightedTextColor returns different colors
+        // depending on window focus, which does not apply to this applet
+        // instead, we use palette.highlightedText here, which returns consistent result
+        color: background.state == MenuDelegate.State.Rest ? palette.windowText : palette.highlightedText
     }
 }

[Nicolás Alvarez]

This came from !1616 (merged), but it had to be re-pushed to squash it so GitLab doesn't show the MR number.