Add images to docs for public API classes of controls and missing examples

The JavaDoc for various controls (Button, ComboBox, TableView...) could really benefit from a representative picture (screenshot) of the control.

Developers that read the class description would like to know what the control looks like and seeing it is more helpful than the sentence describing it.

This was done back in AWT (e.g., https://docs.oracle.com/javase/10/docs/api/java/awt/TextArea.html), but not in Swing.