This extends the popup menu to accept image or icon configurations a la `StatusIconSettings`
and `StatusImageSettings` in menu items, as well as nested menus.
Usage:
```qml
StatusPopupMenu {
StatusMenuItem {
text: "Custom Image icon"
image.source: // image source
}
StatusMenuItem {
text: "Custom identicon icon"
image.source: // identicon source
image.isIdenticon: true
}
StatusMenuItem {
text: "Custom letter identicon"
iconSettings.isLetterIdenticon: true
iconSettings.background.color: "red"
}
}
```
Few things to note:
- Because `StatusMenuItem` is an `Action` type, we can't extend its `icon` property,
so we have to introduce our own (`iconSettings`) which can be of type `StatusIconSettings`
- Where possible, `StatusPopupMenu` will prefer `iconSettings.[...]` over `icon.[...]`,
which means, both would work: `icon.name` and `iconSettings.name`.
This is for consistency's sake. Consumers can switch completely to `iconSettings` if desired.
- When `isLetterIdenticon` is true, `iconSettings.background.color` must be set, similar
to how it work in any other StatusQ component that makes use of this configuration type.
Closes#263