Add R support to Sandbox

[fangfy]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
Installation of R in the environment
Add R kernel to Jupyter so users can select R when starting a notebook
Installation of the sits R package (https://github.com/e-sensing/sits/) and probably also sitsdata (to be confirmed)

Additional context
This gives option for users to use R as in the examples at:
https://www.kaggle.com/esensing/introduction-to-sits
https://www.kaggle.com/esensing/raster-classification-in-sits

With some additional libraries installed, it might be possible to program with both languages in same notebook:
https://anderfernandez.com/en/blog/how-to-program-with-python-and-r-in-the-same-jupyter-notebook/