Add path substring filtering

Handle cases where we want to check everything *but* a given
substring.

src/smgdc/app.py

@@ -61,6 +61,13 @@ def main() -> None:
         action="append",
         help="Filters configs to only those that match the given substring",
     )
+    parser.add_argument(
+        "--no-match",
+        dest="no_matches",
+        type=str,
+        action="append",
+        help="Filters configs matching the given substring",
+    )
     parser.add_argument(
         "--fail-fast",
         action="store_true",
@@ -105,6 +112,8 @@ def main() -> None:
 
         if args.matches and not any(match in header for match in args.matches):
             continue
+        elif args.no_matches and any(match in header for match in args.no_matches):
+            continue
 
         print(header)