Allow run action to bind mount additional directories

[oSoMoN]

When run in chroot, the run action will bind mount the script's parent directory to /tmp/script inside the chroot.

In some cases, it might be useful to allow bind mounting additional subdirectories of the recipe.

One use case is a script that optionally installs locally-built packages. This is currently possible but one has to put these packages under (a subdirectory of) the script's parent directory, which might not be ideal if one wants to keep the scripts in one place and local artifacts in a separate place.

[obbardc]

$RECIPEDIR and $ARTIFACTDIR should also be mounted for a run action. Can you check if I am remembering correctly?

[oSoMoN]

That's only when chroot == false, afaict.

[obbardc]

That's only when chroot == false, afaict.

Right, thought so. It'd be trivial to add that functionality.

[oSoMoN]

I could give it a go. Do you suggest bind mounting the entire $RECIPEDIR always, or going with my initial suggestion to add an optional property to the action for callers to selectively list directories to mount?