Change interactive tutorial status to planned

[coatless]

Per the now public details:

https://mstdn.social/@gws/112678999487222215

[cscheid]

This is a bit complicated - webr is developed by George, who's a Posit employee, but he's not on the Quarto team, and webr-related things are not core to Quarto yet.

I don't want to change this to planned because it would put pressure on him from us to do it, and I don't think that's the right to do.

[cwickham]

Now it's announced, I've updated to Quarto Live Extension via https://github.com/quarto-dev/quarto-web/pull/1307