weldr-client has replaced composer-cli so remove all of the code and
tests, adjust various things so they don't expect it to be available,
and rename some things like test/composertest.py to reflect its
exclusive use by lorax.
(cherry picked from commit b75b692607)
This builds a boot.iso in the vm, copies it out, and boots it.
The tests that run inside the boot.iso
(/tests/lorax/test_boot_bootiso.sh) cannot use beakerlib so it needs to
be a simple shell script returning 1 on failure along with a descriptive
message.
