images: Add some Cockpit runtime and test deps to centos-9-bootc

This will allow us to install cockpit-ws.rpm and run networking and
metrics tests.

Also toss in strace as the ultimate debugging tool, and rsync for
`build.js -r` and a more efficient bots API.

See cockpit-project/cockpit#21561

images/scripts/lib/bootc.Containerfile

@@ -2,9 +2,11 @@ ARG base_image
 FROM $base_image
 
 # pre-install the distro version, which is useful for testing extensions and manual experiments
+# also pre-install ws and test dependencies
 RUN \
     dnf update -y --exclude='kernel*' && \
     dnf install -y --setopt install_weak_deps=False cockpit-system cockpit-networkmanager && \
+    dnf install -y dnsmasq pcp python3-pcp rsync sscg strace wireguard-tools && \
     dnf clean all
 
 ADD lib/mcast1.nmconnection /usr/lib/NetworkManager/system-connections/