This adds a basic skeleton to test various tvix components in
combination.
As a first start, we test the virtiofs integration, by seeding the tvix-
store with some data, booting a VM, and listing the contents from there.
Change-Id: Ice6516d0eb508d19ea8fabefee860a0950046171
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9449
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>