Add code tabs for scala3-book/taste-repl

[byyue]

See #2481:
Scala 3 Book -> A Taste of Scala -> The REPL.

[bishabosha]

Thank you very much! The suggestions I made are just to make it more maintainable

[byyue]

Thank you for the review! I have another thought: to set the Scala 3 tab as the default, at least in the Scala 3 Book. That's why I put it before the Scala 2 tab.

@julienrf Do you consider it wise to unify this kind of format?

[bishabosha]

For me personally numbers ascending left to right across the tabs makes sense, but maybe others would object - but if we chose to change the convention then that should be done globally across the site in a separate PR.

As time goes on we will likely rebrand the book to just the Scala Book when we have updated enough code examples

[bishabosha]

Thanks a lot!