Support local::

[chainsawriot]

I would say all ingredients are there already. But we need to give warnings

• when local:: is used for resolve(), remind users that this is not reproducible on another machine where the local package is not available.
• When dockerize(), enforce cache and transfer the local packages in the raw tarball format (don't R CMD build locally, do it inside the container, like how we treat GitHub packages now).

Tag v0.2 for now. But don't know how tedious it can be.

[chainsawriot]

It makes sense now to implement this

https://github.com/chainsawriot/rang/blob/a9bb93505655c4e39d89b6f94285349a0e5fcf8c/R/as_pkgs.R#L42-L48

[chainsawriot]

27-02: I will work on this first, to complete the entire implementation of pkgrefs.

[chainsawriot]

• parse and resolve
• sessionInfo
• renv (read)
• dockerize (enforce cache)
• Does the container work?
• .write_rang_as_comment adds a comment that rang with local packages is not reproducible.