Add LockTokenParser::parseIfCondition method and corresponding tests

- Implemented the `parseIfCondition` method in `LockTokenParser` to extract lock tokens from `if` headers.
- Added `LockTokenParserTest` with multiple test cases using data providers to validate parsing logic, including scenarios with no headers, resource URIs, and "not" conditions.

src/Bundle/ChillDocStoreBundle/Dav/Utils/LockTokenParser.php

@@ -40,4 +40,19 @@ final readonly class LockTokenParser
 
         return $token;
     }
+
+    public function parseIfCondition(Request $request): ?string
+    {
+        $if = $request->headers->get('if');
+
+        if (null === $if) {
+            return null;
+        }
+
+        if (preg_match('/\((?:not\s+)?<([^>]+)>/i', $if, $matches)) {
+            return $matches[1];
+        }
+
+        return null;
+    }
 }