Add support for INLA package

[Timmimim]

INLA must be installed from a specific repo, see http://www.r-inla.org/download

install.packages("INLA", repos=c(getOption("repos"), INLA="https://inla.r-inla-download.org/R/stable"), dep=TRUE)

This should be supported both during predetect (https://github.com/o2r-project/containerit/blob/b4a05fa37bc003a11f7822ed2b257fbe38f0def1/R/sessionInfo-localbuild-methods.R#L137) and for the Dockerfile generation.

A short term solution would be to install the package in containerit's Docker images.

Alternatively (but potentially even more hacky), the predetect could also use the same installation commands in the Rmd file.

[reported by @nuest]