make changes to pycharm section to reflect connecting to levante, revamp RStudio Section completely

Make changes to pycharm section to reflect connecting to levante, revamp RStudio section completely, as previous method was not possible on Levante.

New method is using the R extension(s) available for VS Code, which allows working and executing R code remotely.

The updated slides are available under following artifact:

https://freva.gitlab-pages.dkrz.de/-/plugins4freva/plugin_workshop/dissecting-a-freva-plugin/-/jobs/354706/artifacts/public/index.html