[JEWEL-954] Implement ad text in popups

[wellingtoncosta]

Summary

This PR introduces a new component called PopupAdText, which is designed to be used inside a popup container to give a more informative and/or helpful description to that menu. To apply that, a new parameter called adText was introduced to all public API of comboboxes, so no need to setup layout, spacing and stuff like that. This API is designed to be simpler as we have in AbstractPopup#setAdText method in the legacy Swing implementation.

Screenshot

Release notes

⚠️ Important Changes

• Added the new PopupAdTextStyle to the JewelTheme and to the IntUiTheme
• Introduced a new PopupAdText component

New features

• Popups can now have a ad text in which can be used to add more description to a combobox options list or even give more context on such menu.

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Note

Adds optional ad text to popups and combo boxes with full theming support.

• New PopupAdText component and PopupAdTextStyle (colors/metrics/textStyle) with LocalPopupAdTextStyle and JewelTheme.popupAdTextStyle
• PopupContainer now renders bottom adText; ComboBox, ListComboBox, and EditableListComboBox APIs gain optional adText plumbed through implementations
• Theme integration: DefaultComponentStyling extended with popupAdTextStyle; IntUiTheme (light/dark) and Swing bridge provide style (readPopupAdTextStyle, standalone light()/dark())
• Samples: showcase adds "Editable list combo box with ad text" example

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[faogustavo]

I think that you are missing the LaF styles loading. Also, make sure to get values to match the theme.

For more details in the AdText styles, check the JBUI.CurrentTheme.Advertiser type. You can find its usage to use as baseline on this function public void setAdText(@NotNull @NlsContexts.PopupAdvertisement String s, int alignment)