tests/content-origins: Verify expected vendor for all RPM packages

As we move to support multiple streams (particularly for C9S versus RHEL)
we should ensure that we're not accidentally including content
from CentOS in official RHEL builds, and vice versa.  The RPM vendor
field is useful for this.

For now, this test just verifies Fedora and RHEL vendors, and I
tested on both.

tests/kola/content-origins/data/commonlib.sh

@@ -0,0 +1 @@
+../../data/commonlib.sh

tests/kola/content-origins/test.sh

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+#!/bin/bash
+# kola: {"platforms": "qemu", "exclusive": false }
+# Verify the RPM %{vendor} flag for everything installed matches what we expect.
+#
+# - platforms: qemu
+#   - This test should pass everywhere if it passes anywhere.
+
+set -xeuo pipefail
+
+. $KOLA_EXT_DATA/commonlib.sh
+
+. /usr/lib/os-release
+
+case "${ID}" in
+    fedora) vendor='Fedora Project';;
+    rhel|rhcos) vendor='Red Hat, Inc.';;
+    *) echo "Unknown operating system ID=${ID}; skipping this test"; exit 0;;
+esac
+
+cd $(mktemp -d)
+rpm -qa --queryformat='%{name},%{vendor}\n' > rpmvendors.txt
+if grep -vF ",${vendor}" rpmvendors.txt > unmatched.txt; then
+    echo 1>&2 "Expected only vendor ${vendor} for all packages"
+    cat unmatched.txt
+fi
+