Accessible Label Component

The AccessibleLabel component allows the a11y label property to be specified separately from other a11y properties.

In most apps, the label property comes from application code rather than library code. However, the design of accesskit requires that all a11y properties be stored in a single large data structure contained in the AccessibilityNode component. This creates a usability conflict with BSN and other methods of spawning complex hierarchies, where composing multiple components is the primary means of behavioral reuse.

By putting the label in its own component, it can be used as a mixin within BSN templates, allowing the label to be added by the widget user rather than the widget author.

Internally, this uses component hooks to sync the AccessibilityNode properties with the payload of the AccessibleLabel component, satisfying the needs of accesskit.