Initial setup work for system tests

tests/WebApi.Tests.System/Dockerfile.keycloak

@@ -0,0 +1,8 @@
+FROM registry.access.redhat.com/ubi9 AS ubi-micro-build
+RUN mkdir -p /mnt/rootfs
+RUN dnf install --installroot /mnt/rootfs curl --releasever 9 --setopt install_weak_deps=false --nodocs -y && \
+    dnf --installroot /mnt/rootfs clean all && \
+    rpm --root /mnt/rootfs -e --nodeps setup
+
+FROM quay.io/keycloak/keycloak
+COPY --from=ubi-micro-build /mnt/rootfs /