containers/ws: Include cockpit-files

This brings the ws container closer to the Client flatpak. In beiboot
mode, Files works everywhere including RHEL 8 [1].

[1] cockpit-project/cockpit-files#917

containers/ws/install.sh

@@ -17,6 +17,10 @@ storaged
 system
 "
 
+EXTERNAL_COCKPIT_PACKAGES="
+cockpit-files
+"
+
 dnf install -y 'dnf-command(download)' cpio
 $INSTALL coreutils-single util-linux-core sed sscg python3 openssh-clients
 
@@ -44,5 +48,10 @@ else
     rm $INSTALLROOT/usr/libexec/cockpit-session
 fi
 
+for rpm in $EXTERNAL_COCKPIT_PACKAGES; do
+    dnf download $rpm
+    unpack $rpm-*.rpm
+done
+
 rm -rf /build/var/cache/*dnf* /build/var/lib/dnf /build/var/lib/rpm* /build/var/log/*
 rm -rf /container/rpms || true