Convert the test to use `pytest` and split out the individual
tests. The temp-directory fixture has the session scope so
that checkpoints can be shared between the individual tests.
Extend the current ostree container test case to use the new
bootiso manifest to build a bootable iso. This is done in the
existing container test case in order to share the build root
and ostree commit results and speed up testing. In the future,
the test infrastructure should be extended so that the cache
can be optionally shared between test cases.
Add a v2 manifest to builds an ostree commit, then builds a small
container with a webserver and puts that commit into it.
Start a new test suit where this manifest is built and then checked
that the artifact exists. In the future the artifact should also be
inspected and run by a container engine and the commit be pulled
via ostree.
