[Component] - Dropdown + Combobox, label behaviour

[Powerplex]

On components like Input, when you click on it's FormField label, it focuses the input, and if you hover the label, it apply hover styles to the input.

This is not the case on Dropdown + Combobox.

The reason is:

• for Spark, label is part of FormField.
• for Downshift (lib used for Dropdown and Combobox) label is part of the anatomy of the component and it is using getLabelProps(). For now, we apply the props returned by this function to a hidden label.

We should find a way to apply downshift props on the FormField label, or something similar.