Move resolving git reference to config validation

Instead of multiple places handling the same thing duplicating the
logic, it's better to do it once upfront. This allows easy caching of
the results.

Additional advantage of this approach is that the config dump will
include resolved URLs. The original reference will still be available in
the copy of the original config.

JIRA: COMPOSE-3065
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

bin/pungi-config-validate

@@ -77,11 +77,11 @@ def read_variants(compose, config):
             compose.all_variants[child.uid] = child
 
 
-def run(config, topdir, has_old):
+def run(config, topdir, has_old, offline):
     conf = kobo.conf.PyConfigParser()
     conf.load_from_file(config)
 
-    errors, warnings = pungi.checks.validate(conf)
+    errors, warnings = pungi.checks.validate(conf, offline=offline)
     if errors or warnings:
         for error in errors + warnings:
             print(error)
@@ -146,10 +146,15 @@ def main(args=None):
                         help='configuration file to validate')
     parser.add_argument('--old-composes', action='store_true',
                         help='indicate if pungi-koji will be run with --old-composes option')
+    parser.add_argument(
+        "--offline",
+        action="store_true",
+        help="Do not validate git references in URLs",
+    )
     opts = parser.parse_args(args)
 
     with pungi.util.temp_dir() as topdir:
-        errors = run(opts.config, topdir, opts.old_composes)
+        errors = run(opts.config, topdir, opts.old_composes, opts.offline)
 
     for msg in errors:
         print(msg)