add support for the dump plugin in kas-container

This patch adds support to use the dump plugin in kas-container.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

container-entrypoint

@@ -40,7 +40,7 @@ fi
 
 if [ -n "$1" ]; then
 	case "$1" in
-	build|checkout|for-all-repos|menu|shell|-*)
+	build|checkout|dump|for-all-repos|menu|shell|-*)
 		# SC2086: Double quote to prevent globbing and word splitting.
 		# shellcheck disable=2086
 		exec $GOSU kas "$@"