Feature: #106092 - Associative array keys for TCA valuePicker items 

See forge#106092

Description 

It is now possible to define associative array keys for the items configuration of the TCA type valuePicker. The new keys are called label and value.

This follows the change made previously to the items configuration of the TCA types select, radio, and check. See forge#99739.

Impact 

The TCA items configuration can now be defined in a more consistent and readable way using associative array keys. This eliminates ambiguity about whether the label or value comes first.

Optional keys such as icon, group, or description can be used as needed.