[Feature]: allow to define multiple times the same header in route.fulfill

🚀 Feature Request

There is currently no way to define multiple times the same header in route.fulfill.

I first hoped I could trick it by using different cases but com/microsoft/playwright/impl/RouteImpl.java:214 uses headers.put(h.getKey().toLowerCase(), h.getValue());

I would expect that I can define headers in both ways, via Map<String, String> or via List<HttpHeader> (likewise one can use response.allHeaders() and response.headersArray()

Example

I have a test where I want to make sure that my implementation to detect multiple headers work. That's why I use route.fulfill and would like to define a header multiple times.

Motivation

see above

com/microsoft/playwright/impl/RouteImpl.java の214行目から始め、route.fulfill が Map<String, String> と List をどのように処理するかを追跡します。response.allHeaders() および response.headersArray() と動作を比較します。route.fulfill が要求された両方の入力形式で重複するヘッダー名を保持できれば完了です。