Added setCookie. (#6197)

Author: limingxinleo

src/Server/Response.php

@@ -47,6 +47,15 @@ public function withCookie(Cookie $cookie): static
  return $clone;
  }
 
+ /**
+ * Returns an instance with specified cookies.
+ */
+ public function setCookie(Cookie $cookie): static
+ {
+ $this->cookies[$cookie->getDomain()][$cookie->getPath()][$cookie->getName()] = $cookie;
+ return $this;
+ }
+
  /**
  * Retrieves all cookies.
  */