If one of the chroot mounts fails to unmount, keep iterating so that we
don't stop and continue to unmount the rest.
Print an error message with the failed mounts, but don't fail the build.
Since failing to unmount doesn't fail the exiting of the context, and
the context itself doesn't know what will be running in the chroot,
do a lazy unmount.
New chroot utility module that sets up a tree with the necessary virtual
filesystems needed for running commands in the root tree in a similar
environment as they would run in the build root.
This is needed for some stages, but may also be used for all chroot
calls to unify the setup and teardown of the root environment.
The Chroot context class was previously part of the org.osbuild.dracut
stage, which was the first stage to need this setup.
