IssueTracker

As far as I see, there is way to style the background of a `DropdownMenuItem`. It is useful in some cases to set an item apart from others, for example to indicate selection of a particular item. For example, it could be added as a field in `MenuItemColors`.

The implementation emits a `Row` which does not set a background color.

Setting background of the `text` and leading / trailing icon components would leave padding gaps.