Label is a base class for actions and categories.
Label icon. Treated as URL if contains
/ or as a CSS class otherwise. E.g.
fas fa-wrench would be treated as a CSS class.
Notification to display next to the label. E.g. a number of new messages in an inbox.
For some label representations specifies that the label shall be displayed as an outline instead of a solid fill.
Can be used for cusomization of label appearance in addition to “built-in” label appearance attributes - color and outline.