config-dump: Allow freezing koji event

Accept similar argument to pungi-koji: either direct event ID, or a path
to a compose from which the event will be extracted.

It would be nice if we could reuse the path to compose given as source,
but there may be more that one compose, so ultimately we need a way to
overwrite it anyway.

JIRA: COMPOSE-3278
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

bin/pungi-config-dump

@@ -10,6 +10,7 @@ import sys
 
 import kobo.conf
 import pungi.checks
+import pungi.util
 
 
 def load_file(source, conf):
@@ -38,6 +39,15 @@ def main():
             "or arbitrary number of config files."
         ),
     )
+    parser.add_argument(
+        "--freeze-event",
+        metavar="ID",
+        type=pungi.util.parse_koji_event,
+        help=(
+            "Include this koji event in the created config; "
+            "takes either event ID or path to a compose"
+        ),
+    )
     group = parser.add_mutually_exclusive_group()
     group.add_argument(
         "--just-dump",
@@ -65,6 +75,9 @@ def main():
                 print(error, file=sys.stderr)
             return False
 
+    if args.freeze_event:
+        conf["koji_event"] = args.freeze_event
+
     json.dump(conf, sys.stdout, sort_keys=True, indent=4)
     return True