New predefined option "Select All" for the Select

[GomezIvann]

Commonly, our Select component is used as a filter. For example, the new DxcBarChart filters the displayed data. In those scenarios where you select and unselect almost all the options, the need arises for an option that selects them all at once.

https://www.delldesignsystem.com/components/dropdown/?tab=Design

The task here would be to investigate how to approach this functionality, from both design and implementation perspectives.

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[GomezIvann]

From our designer Irene:

Functional Requirements

• Placement: The "Select All" option should be placed at the top of the dropdown list for easy access.
• Behavior:
  • When "Select All" is clicked, all individual items in the dropdown are selected.
  • When "Deselect All" (same "Select All" option) is clicked again, all individual items in the dropdown are deselected.
• Visibility: The "Select All" option should always be visible when the dropdown is expanded.
• The prop is gonna be called enableSelectAll.