tests: Add nvr checking into a shared library

can be used for conditionally enabling parts of the test scripts:

source /usr/libexec/tests/osbuild-composer/shared_lib.sh

if nvrGreaterOrEqual "osbuild-composer" "41"; then
    .... do some more testing ...
fi

osbuild-composer.spec

@@ -408,6 +408,7 @@ Requires:   libvirt-daemon-driver-storage-disk
 Requires:   libvirt-daemon-kvm
 Requires:   qemu-img
 Requires:   qemu-kvm
+Requires:   rpmdevtools
 Requires:   virt-install
 Requires:   expect
 Requires:   python3-lxml

test/cases/shared_lib.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/bash
+
+function nvrGreaterOrEqual {
+    local rpm_name=$1
+    local min_version=$2
+
+    set +e
+
+    rpm_version=$(rpm -q --qf "%{version}" "${rpm_name}")
+    rpmdev-vercmp "${rpm_version}" "${min_version}"
+    if [ "$?" != "12" ]; then
+        # 0 - rpm_version == min_version
+        # 11 - rpm_version > min_version
+        # 12 - rpm_version < min_version
+        echo "DEBUG: ${rpm_version} >= ${min_version}"
+        set -e
+        return
+    fi
+
+    set -e
+    false
+}