ci: Rework to split build/test

Aiming to fix #506

I think the problem here may be related to the fact that
we're trying to do all of our CI as part of a build.

Instead, let's function like e.g. the CI for coreos/rpm-ostree
which creates a derived container from the source code.  For
us, this derived container is basically the 2-tuple (source, cosa).

For coreos/rpm-ostree we actually do generate binaries as well
as test code from the buildroot, i.e. a 3 tuple (binaries, test binaries, cosa).
But here we don't need that, there's no actual "build" step.

Split off `validate.sh` as a separate thing that can be a
clearly separate step.

ci/Dockerfile

@@ -0,0 +1,5 @@
+# For CI on a config git repo, all we need to do is combine
+# the source code with coreos-assembler into an image to test.
+FROM registry.svc.ci.openshift.org/coreos/coreos-assembler:latest
+WORKDIR /src
+COPY . .

ci/build-test-qemu.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+set -xeuo pipefail
+# Prow jobs don't support adding emptydir today
+export COSA_SKIP_OVERLAY=1
+# We generate .repo files which write to the source, but
+# we captured the source as part of the Docker build.
+# In OpenShift default SCC we'll run as non-root, so we need
+# to make a new copy of the source.  TODO fix cosa to be happy
+# if src/config already exists instead of wanting to reference
+# it or clone it.  Or we could write our .repo files to a separate
+# place.
+tmpsrc=$(mktemp -d)
+cp -a /src ${tmpsrc}/src
+# Create a temporary cosa workdir
+cd $(mktemp -d)
+cosa init ${tmpsrc}/src
+# TODO query the 4-8 bits from manifest.yaml or so
+curl -L http://base-4-8-rhel8.ocp.svc.cluster.local > src/config/ocp.repo
+cosa fetch
+cosa build
+cosa kola --basic-qemu-scenarios
+cosa kola run 'ext.*'
+# TODO: all tests in the future, but there are a lot
+# and we want multiple tiers, and we need to split them
+# into multiple pods and stuff.

ci/build-test.sh

@@ -0,0 +1 @@
+validate.sh

ci/validate.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+set -xeuo pipefail
+# First ensure submodules are initialized
+git submodule update --init --recursive
+# Basic syntax check
+./fedora-coreos-config/ci/validate