enable arm64 Docker builds

[cjyetman]

closes #104

Use a base image that has arm64 versions available and do not explicitly set the platform to amd64

RStudio and tidyverse provided by rocker/tidyverse and rocker/rstudio are not strictly necessary (necessary tidyverse R packages are installed anyway as dependencies).
https://hub.docker.com/r/rocker/r-ver/tags

[AlexAxthelm]

I've nearly got the build process for multiarch builds in workflow.pacta. (RMI-PACTA/workflow.pacta#41). Suggest pausing this one until that's working as intended.

[cjyetman]

I've nearly got the build process for multiarch builds in workflow.pacta. (RMI-PACTA/workflow.pacta#41). Suggest pausing this one until that's working as intended.

How is workflow.pacta relevant to this repo?

[AlexAxthelm]

Because when that gets resolved, we can use the same action to do CI builds on this repo (including arm64)

[cjyetman]

oh... but this PR isn't about a GH action, it's about running the Dockerfile using docker-compose up

[jdhoffa]

I don't have context or understand the discussion here, so leave it to @AlexAxthelm to review.

[cjyetman]

@AlexAxthelm?

[cjyetman]

holding in draft because getting/building arm64 linux R packages is still wonky

[cjyetman]

closing this as arm64 linux binaries on Public Posit Package Manager is not on the short term roadmap: https://forum.posit.co/t/arm64-binary-packages-for-linux-in-posit-public-package-manager/178514