[System] HttpListenerRequest: ignore bad cookies and keep request alive (#5657)

[System] HttpListenerRequest: ignore bad cookies and keep request alive (#5657)

HttpRequestListener throws on incorrect cookie name. It throws CookieException ("Name contains invalid characters"). There are many cookies out there that unfortunately do not conform to the guidelines and HttpRequestListener will kill the request in such a case. The .Net framework under windows lets the request through however.

Included is a patch HttpListenerRequest as well as a test with a bad cookie name.

I have tested this under linux(master branch) and .net (4.0), they now both have the same behavior.