Improve configuration style toggle in documentation

[fmbenhassine]

Currently, the toggle that switches the configuration style between Java and XML is a simple horizontal radio button at the top of each page:

While this does what it was designed for, it still a bit inconvenient if we want to change the configuration style of a sample at the middle/bottom of the page (ie need to go up, change the style, go back down to the sample). It would be great if the radio button is restyled as those used in other projects of the portfolio. Here is an example from Spring Framework docs:

Restyling the button would improve consistency and also the user experience.

[fmbenhassine]

Done as part of #4422