Adding support to combine cookie header

[mrsaldana]

• I have considered the risk of behavior change or other zero migration impact (https://github.com/OpenLiberty/open-liberty/wiki/Behavior-Changes).
• If this PR fixes an Issue, the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN" (verify release bug label if applicable: https://github.com/OpenLiberty/open-liberty/wiki/Open-Liberty-Conventions).
• If this PR resolves an external Known Issue (including APARS), the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN".

HTTP requests containing multiple Cookie headers were not being processed correctly. According to RFC 6265, "the user agent MUST NOT attach more than one Cookie header field".

Netty's default behavior only considers the first Cookie header, leading to issues when multiple Cookie headers are present.

This PR adds a CombinedCookieHandler to intercept the FullHttpRequest and combine multiple Cookie headers.