Unfortunately this libclang-dev error is tricky. You can try some of the ideas in this similar thread where we tried to debug the same issue on Ubuntu 19.04 (thus far unsuccessfully).
@ezio Have you ever installed RStudio on this machine before? Could you see if you can install RStudio 1.1 or other previous versions?
wget http://download1.rstudio.org/rstudio-1.1.463-amd64.deb
More resources: