Add a JS event listener to the interactive radio button example

[aminalhazwani]

The current radio buttons page on staging features an interactive example accessible via the image caption.

We would like to append a GA JS event in order to understand if this is something we should purse more. The things that we would like to measure are two: first if users actually use the caption and switch from the static image to the interactive example and second, once they switch, if they actually interact with said example.

Side note: we might change the code of the interactive example, would that be possible also after the JS events are set up?

[ericawright]

In order to set up the second case - interacting with the example - I need to remove the iframe. So yes, the code can change, and will have to change

[aminalhazwani]

@ericawright ok, thanks for the feedback! So for now let's keep the iframe and track only the interaction with the image caption ☺️