add multiarch image / arm support

[maxheld83]

especially for people using Apple Silicon, it might be convenient to have a multiarch image with arm support (ie. linux/arm64 or something).

If I understand this correctly, using the existing linux/amd64 image on Apple Silicon would involve some kind of emulation (QEMU? Rosetta? Both? I don't know ...), which may carry a (further) performance penalty.

The official r-base seems to have this.

[JosiahParry]

I think this may be my challenge. I am unable to build docker images which use FROM rstudio/rbase:bionic due to differing platforms.

[eitsupi]

It cannot be built unless the arm64 R installer is provided.

r-docker/4.1/focal/Dockerfile

Line 14 in e35d1e5

RUN wget https://cdn.rstudio.com/r/${OS_IDENTIFIER}/pkgs/r-${R_VERSION}_1_amd64.deb && \