spec for defining actions and assets

[vsoch]

This might be another project, but arguably I should be able to selectively pick blobs from an ORAS artifact, and then specify where I want them in my container. E.g.,:

• take the aws-cli binary and put in /usr/local/bin
• move this entire config directory here
• get the annotation XYZ and turn it into a file here

Since these actions need to happen inside the container, we likely can't rely on making many mounts, but rather there could be a binary that is injected into the container by the driver, and then the binary takes a manifest of instructions (akin to the above) and a path to the mounted directory, and does the operations for the mount.